feat: Add MinIO endpoint/public URL configuration via settings UI

Store endpointUrl and publicUrl in cloudinary_config DB table so
MinIO connection can be fully configured from the app settings
without needing environment variables.

- DB migration: adds endpoint_url and public_url columns
- Schema: adds endpointUrl/publicUrl to cloudinaryConfig table
- MinIO service: reads endpoint from DB (falls back to MINIO_ENDPOINT env)
- buildMinioUrl: accepts optional publicUrl override from DB config
- All routes updated to pass config.publicUrl to buildMinioUrl
- Settings UI (desktop + mobile): adds Endpoint URL and Public URL fields

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/migrate.ts

@@ -111,6 +111,18 @@ export async function migrate() {
       ALTER TABLE "posts"
       ADD COLUMN IF NOT EXISTS "generation_error" text;
     `);
+
+    // cloudinary_config.endpoint_url (MinIO internal endpoint URL)
+    await client.query(`
+      ALTER TABLE "cloudinary_config"
+      ADD COLUMN IF NOT EXISTS "endpoint_url" text;
+    `);
+
+    // cloudinary_config.public_url (MinIO public-facing base URL)
+    await client.query(`
+      ALTER TABLE "cloudinary_config"
+      ADD COLUMN IF NOT EXISTS "public_url" text;
+    `);
     // page_analytics_history.page_engagement
     await client.query(`
       ALTER TABLE "page_analytics_history"