feat: add no-sales-6-months tab to stock management page

Adds a second tab "Sans vente 6 mois" on the grid page listing all
products with no sale in the last 6 months, sorted by oldest last
sale first. Resolves merge conflicts from upstream refactor.

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

.claude/settings.local.json

@@ -2,8 +2,10 @@
   "permissions": {
     "allow": [
       "Bash(npx tsc:*)",
-      "Bash(find /c/GIT/CollectFlow/src -type f \\\\\\( -name \"*.ts\" -o -name \"*.tsx\" \\\\\\) -exec grep -l \"dernier\" {} \\\\;)",
-      "Bash(rtk tsc:*)"
+      "Bash(rtk tsc:*)",
+      "Bash(rtk grep:*)",
+      "Bash(node_modules/.bin/tsc --noEmit)",
+      "Bash(./node_modules/.bin/tsc --noEmit)"
     ]
   }
 }