Feature: Remplacement de tous les prompts par des modaux + Fix RSS refresh

Modaux :
- Création ConfirmModal pour confirmations avec variants (default/destructive)
- Création InputModal pour saisie de texte/URL/mot de passe
- Création AddUserModal pour création d'utilisateur avec admin checkbox
- Remplacement de tous les prompt() et confirm() par des modaux modernes
- Modaux pour : suppression note, ajout todo, ajout RSS, ajout utilisateur, suppression utilisateur, changement mot de passe, ajout todo dans note

Fix RSS :
- Ajout route POST /api/rss/refresh (alias de /api/rss/fetch)
- Fix uploadImage retour avec result.image || result

UX améliorée :
- Plus de popups navigateur natifs
- Interface cohérente et moderne
- Validation dans les modaux
- Support touche Entrée dans les InputModals
- Auto-focus sur le champ de saisie

src/components/modals/AddUserModal.tsx

@@ -0,0 +1,95 @@
+import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from "@/components/ui/dialog";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { Checkbox } from "@/components/ui/checkbox";
+import { useState, useEffect } from "react";
+import { UserPlus } from "lucide-react";
+
+interface AddUserModalProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  onConfirm: (username: string, password: string, isAdmin: boolean) => void;
+}
+
+export function AddUserModal({ open, onOpenChange, onConfirm }: AddUserModalProps) {
+  const [username, setUsername] = useState("");
+  const [password, setPassword] = useState("");
+  const [isAdmin, setIsAdmin] = useState(false);
+
+  useEffect(() => {
+    if (open) {
+      setUsername("");
+      setPassword("");
+      setIsAdmin(false);
+    }
+  }, [open]);
+
+  const handleConfirm = () => {
+    if (username.trim() && password.trim()) {
+      onConfirm(username.trim(), password.trim(), isAdmin);
+      onOpenChange(false);
+    }
+  };
+
+  const isValid = username.trim().length > 0 && password.trim().length > 0;
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="sm:max-w-[425px]">
+        <DialogHeader>
+          <DialogTitle className="flex items-center gap-2">
+            <UserPlus className="h-5 w-5" />
+            Ajouter un utilisateur
+          </DialogTitle>
+          <DialogDescription>
+            Créez un nouveau compte utilisateur pour l'application
+          </DialogDescription>
+        </DialogHeader>
+        <div className="grid gap-4 py-4">
+          <div className="grid gap-2">
+            <Label htmlFor="username">Nom d'utilisateur</Label>
+            <Input
+              id="username"
+              placeholder="Nom d'utilisateur"
+              value={username}
+              onChange={(e) => setUsername(e.target.value)}
+              autoFocus
+            />
+          </div>
+          <div className="grid gap-2">
+            <Label htmlFor="password">Mot de passe</Label>
+            <Input
+              id="password"
+              type="password"
+              placeholder="Mot de passe"
+              value={password}
+              onChange={(e) => setPassword(e.target.value)}
+            />
+          </div>
+          <div className="flex items-center space-x-2">
+            <Checkbox
+              id="is-admin"
+              checked={isAdmin}
+              onCheckedChange={(checked) => setIsAdmin(checked as boolean)}
+            />
+            <Label
+              htmlFor="is-admin"
+              className="text-sm font-medium leading-none peer-disabled:cursor-not-allowed peer-disabled:opacity-70"
+            >
+              Administrateur
+            </Label>
+          </div>
+        </div>
+        <DialogFooter className="gap-2 sm:gap-0">
+          <Button variant="outline" onClick={() => onOpenChange(false)}>
+            Annuler
+          </Button>
+          <Button onClick={handleConfirm} disabled={!isValid}>
+            Créer l'utilisateur
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}

src/components/modals/ConfirmModal.tsx

@@ -0,0 +1,57 @@
+import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from "@/components/ui/dialog";
+import { Button } from "@/components/ui/button";
+import { AlertTriangle } from "lucide-react";
+
+interface ConfirmModalProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  title: string;
+  description: string;
+  onConfirm: () => void;
+  confirmText?: string;
+  cancelText?: string;
+  variant?: "default" | "destructive";
+}
+
+export function ConfirmModal({
+  open,
+  onOpenChange,
+  title,
+  description,
+  onConfirm,
+  confirmText = "Confirmer",
+  cancelText = "Annuler",
+  variant = "default"
+}: ConfirmModalProps) {
+  const handleConfirm = () => {
+    onConfirm();
+    onOpenChange(false);
+  };
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="sm:max-w-[425px]">
+        <DialogHeader>
+          <DialogTitle className="flex items-center gap-2">
+            {variant === "destructive" && <AlertTriangle className="h-5 w-5 text-destructive" />}
+            {title}
+          </DialogTitle>
+          <DialogDescription>
+            {description}
+          </DialogDescription>
+        </DialogHeader>
+        <DialogFooter className="gap-2 sm:gap-0">
+          <Button variant="outline" onClick={() => onOpenChange(false)}>
+            {cancelText}
+          </Button>
+          <Button
+            variant={variant}
+            onClick={handleConfirm}
+          >
+            {confirmText}
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}

src/components/modals/InputModal.tsx

@@ -0,0 +1,89 @@
+import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from "@/components/ui/dialog";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { useState, useEffect } from "react";
+
+interface InputModalProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  title: string;
+  description?: string;
+  label: string;
+  placeholder?: string;
+  defaultValue?: string;
+  onConfirm: (value: string) => void;
+  confirmText?: string;
+  cancelText?: string;
+  type?: "text" | "password" | "url" | "email";
+}
+
+export function InputModal({
+  open,
+  onOpenChange,
+  title,
+  description,
+  label,
+  placeholder,
+  defaultValue = "",
+  onConfirm,
+  confirmText = "Confirmer",
+  cancelText = "Annuler",
+  type = "text"
+}: InputModalProps) {
+  const [value, setValue] = useState(defaultValue);
+
+  useEffect(() => {
+    if (open) {
+      setValue(defaultValue);
+    }
+  }, [open, defaultValue]);
+
+  const handleConfirm = () => {
+    if (value.trim()) {
+      onConfirm(value.trim());
+      onOpenChange(false);
+      setValue("");
+    }
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === "Enter" && value.trim()) {
+      e.preventDefault();
+      handleConfirm();
+    }
+  };
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="sm:max-w-[425px]">
+        <DialogHeader>
+          <DialogTitle>{title}</DialogTitle>
+          {description && <DialogDescription>{description}</DialogDescription>}
+        </DialogHeader>
+        <div className="grid gap-4 py-4">
+          <div className="grid gap-2">
+            <Label htmlFor="input-field">{label}</Label>
+            <Input
+              id="input-field"
+              type={type}
+              placeholder={placeholder}
+              value={value}
+              onChange={(e) => setValue(e.target.value)}
+              onKeyDown={handleKeyDown}
+              autoFocus
+            />
+          </div>
+        </div>
+        <DialogFooter className="gap-2 sm:gap-0">
+          <Button variant="outline" onClick={() => onOpenChange(false)}>
+            {cancelText}
+          </Button>
+          <Button onClick={handleConfirm} disabled={!value.trim()}>
+            {confirmText}
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}