feat: v6.3.0 API publique complete v2 (REST /api/v2, scopes, OpenAPI)

- Router api_v2.py (~100 endpoints) : tokens, users, workspaces/members,
  collections, pages, proprietes, vues/dashboards, commentaires/mentions,
  notifications, favoris/tags/recents, partage/publish, historique, sprints,
  templates, export/import, forges, recherche FTS, admin, webhooks CRUD
- Helpers api_v2_helpers.py : Bearer unifie (sha256/expires_at/extension_devices),
  scopes hierarchiques read<write<admin, pagination + X-Total-Count, ISO-8601,
  RFC 7807, idempotence, audit, rate-limit par token
- Migration 20 : api_tokens.scopes/expires_at, webhook_deliveries,
  api_audit_log, idempotency_keys
- main.py : handler d'erreurs unifie StarletteHTTPException, /docs + /redoc
- config : PUBLIC_API_INSECURE_OK (dev only), API_V2_RATE_LIMIT_PER_TOKEN
- OpenAPI docs/openapi-v2.json (402 chemins), tests/test_public_api_v2.py (24)
- Docs : CHANGELOG (v6.2.0/6.2.1 clipper + v6.3.0), ROADMAP, API_GUIDE_V6,
  V6_Web_Clipper, README, ARCHITECTURE, /help
- Suite complete 668 verte, ruff OK

app/routers/dashboard.py

@@ -608,6 +608,22 @@ page. If a page with the same title already exists, the offline copy is renamed
 </p>
 </div>
 
+<div class="help-section">
+<h2>🔌 API publique v2</h2>
+<p style="color:var(--text-dim);font-size:14px;line-height:1.6;">
+FlowDeck exposes a full REST API under <b>/api/v2</b> for third-party integrations.<br>
+<b>Auth:</b> create a token in Settings → API tokens, then send it as
+<code>Authorization: Bearer &lt;token&gt;</code>. Tokens carry scopes
+<code>read</code>, <code>write</code> or <code>admin</code> (a higher scope implies the lower ones).<br>
+<b>Features:</b> CRUD on collections, pages, properties, views, comments, notifications,
+favorites, tags, sharing, sprints and templates; pagination (<code>?limit=&amp;offset=</code> +
+<code>X-Total-Count</code>), filters (<code>filter[prop]=value</code>), sorting, full-text search
+(<code>/api/v2/search</code>), idempotency (<code>Idempotency-Key</code>) and RFC 7807 error bodies.<br>
+<b>Reference:</b> interactive OpenAPI docs at <a href="/docs" target="_blank" rel="noopener">/docs</a>
+(also <code>/redoc</code>, <code>docs/openapi-v2.json</code>).
+</p>
+</div>
+
 <div class="help-section">
 <h2>💡 Tips</h2>
 <p style="color:var(--text-dim);font-size:14px;line-height:1.6;">

app/routers/public_api.py

@@ -40,6 +40,9 @@ def verify_token(authorization: str | None = Header(None)):
         raise HTTPException(401, "API token required. Generate one via Settings → API tokens.")
     token = authorization[7:]  # strip "Bearer "
     if token == DEFAULT_TOKEN:
+        from app.config import settings as _s
+        if not _s.public_api_insecure_ok:
+            raise HTTPException(401, "Default token disabled. Set PUBLIC_API_INSECURE_OK=true in dev or use a real Bearer token.")
         return token
     with get_conn() as conn:
         row = conn.execute("SELECT 1 FROM user_tokens WHERE gitea_token=?", (token,)).fetchone()