chore: unify version to 9.7.0 with single source of truth

- Add VERSION file at project root as canonical version source
- Sync all version references: package.json, pyproject.toml, config.py,
  Chart.yaml, docs/CONFIGURATION.md (all were out of sync: 9.0.1, v9.6, 0.1.0)
- Replace hardcoded v9.6 in SettingsPage and About page with dynamic
  APP_VERSION import from @/lib/version.ts
- Add Vite define for __APP_VERSION__ reading from package.json at build time
- Add TypeScript global declaration for __APP_VERSION__

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/settings/SettingsPage.tsx

@@ -12,6 +12,7 @@ import { Input } from '@/components/ui/input'
 import { Label } from '@/components/ui/label'
 import { ChangePasswordForm } from './ChangePasswordForm'
 import { toast } from 'sonner'
+import { APP_VERSION } from '@/lib/version'
 
 function SectionHeader({ icon: Icon, title }: { icon: React.FC<{ className?: string }>; title: string }) {
   return (
@@ -129,7 +130,7 @@ export function SettingsPage() {
             /api/docs (OpenAPI)
           </a>
         } />
-        <InfoRow label="Version" value="v9.6" />
+        <InfoRow label="Version" value={APP_VERSION} />
       </div>
 
       {/* Quick links */}