Fix four defects the screenshots and tests exposed

Verifying the rendered pages rather than the build turned up real bugs:

- The WP-00 health page still sat at src/app/page.tsx and silently won
  the route over the new Aperçu screen, so the home page was a database
  status readout. Moved to /api/sante, where a probe belongs, and wired
  into the compose healthcheck.
- The unassigned row showed a +14 h delta against a contract of zero,
  reading as an overshoot when it is simply the volume left to staff.
  It now shows what there is to fill.
- Two sidebar entries lit at once: an anchor link matched its own page,
  and /equipe matched an employee record. Highlighting now resolves to
  the most specific match, and a test asserts exactly one entry lights
  per screen.
- Section tabs with no built screen pointed at the home page, which
  reads as a broken tab. They now lead to their first entry's
  placeholder.

Also gives truncated compliance alerts a title attribute, so a narrow
cell no longer says there is a problem without saying which.

Playwright can reuse a preinstalled browser through
PLAYWRIGHT_CHROMIUM_PATH when its revision differs from the bundled one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Cr9dkEHwbDgkWPnyGj1Rjv

docker-compose.yml

@@ -37,6 +37,18 @@ services:
       APP_URL: ${APP_URL:-http://localhost:3000}
     ports:
       - '${APP_PORT:-3000}:3000'
+    healthcheck:
+      test:
+        [
+          'CMD',
+          'node',
+          '-e',
+          "fetch('http://127.0.0.1:3000/api/sante').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))",
+        ]
+      interval: 15s
+      timeout: 5s
+      retries: 5
+      start_period: 30s
 
 volumes:
   db-data: