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

playwright.config.ts

@@ -18,7 +18,23 @@ export default defineConfig({
   },
 
   projects: [
-    { name: 'chromium', use: { ...devices['Desktop Chrome'] } },
+    {
+      name: 'chromium',
+      use: {
+        ...devices['Desktop Chrome'],
+        // Certains environnements fournissent déjà un Chromium dont la révision
+        // ne correspond pas à celle qu'attend cette version de Playwright.
+        // PLAYWRIGHT_CHROMIUM_PATH permet de le réutiliser plutôt que d'en
+        // télécharger un second.
+        ...(process.env.PLAYWRIGHT_CHROMIUM_PATH
+          ? {
+              launchOptions: {
+                executablePath: process.env.PLAYWRIGHT_CHROMIUM_PATH,
+              },
+            }
+          : {}),
+      },
+    },
   ],
 
   webServer: {