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/main.py

@@ -8,6 +8,7 @@ from contextlib import asynccontextmanager
 from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
+from starlette.exceptions import HTTPException as _StarHTTPException
 from starlette.middleware.sessions import SessionMiddleware
 
 from app.config import settings
@@ -37,6 +38,7 @@ from app.routers import (
     webhooks,
     workspace,
 )
+from app.routers.api_v2 import router as api_v2_router
 from app.routers.automations import router as automations_router
 from app.routers.collaboration import router as collaboration_router
 from app.routers.emoji import router as emoji_router
@@ -111,9 +113,9 @@ async def lifespan(_app: FastAPI):
 
 app = FastAPI(
     title="FlowDeck",
-    version="6.2.0",
-    docs_url="/docs" if settings.log_level == "DEBUG" else None,
-    redoc_url=None,
+    version="6.3.0",
+    docs_url="/docs",
+    redoc_url="/redoc",
     lifespan=lifespan,
 )
 
@@ -157,6 +159,7 @@ app.include_router(import_page_router)
 app.include_router(permissions_router)
 app.include_router(web_clipper_api_router)
 app.include_router(web_clipper_router)
+app.include_router(api_v2_router)
 
 app.mount("/static", StaticFiles(directory="static"), name="static")
 
@@ -237,12 +240,27 @@ body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;backgrou
 </html>"""
 
 
-@app.exception_handler(404)
-async def not_found_handler(request: Request, exc):
-    """Redirect 404 HTML pages to /workspaces. API routes still get JSON."""
-    # Preserve JSON 404 for all API-like paths (including /db/xxx/api)
-    if "/api" in request.url.path:
-        from fastapi.responses import JSONResponse
-        return JSONResponse({"detail": "Not found"}, status_code=404)
-    from fastapi.responses import RedirectResponse
-    return RedirectResponse("/workspaces", status_code=302)
+@app.exception_handler(_StarHTTPException)
+async def http_exception_handler(request: Request, exc: _StarHTTPException):
+    """Unified handler: RFC7807 for /api/v2, JSON for other /api, redirect for HTML.
+
+    Registered on Starlette's HTTPException (the base class) so it catches both
+    raised exceptions and route-miss 404s.
+    """
+    status = getattr(exc, "status_code", 500)
+    detail = getattr(exc, "detail", str(exc))
+    if status == 404:
+        if request.url.path.startswith("/api/v2"):
+            from app.services.api_v2_helpers import problem_response
+            return problem_response(request, exc)
+        if "/api" in request.url.path:
+            from fastapi.responses import JSONResponse
+            return JSONResponse({"detail": detail if isinstance(detail, str) else "Not found"}, status_code=404)
+        from fastapi.responses import RedirectResponse
+        return RedirectResponse("/workspaces", status_code=302)
+    # Non-404: RFC7807 for /api/v2
+    if request.url.path.startswith("/api/v2"):
+        from app.services.api_v2_helpers import problem_response
+        return problem_response(request, exc)
+    from fastapi.responses import JSONResponse
+    return JSONResponse({"detail": detail if isinstance(detail, str) else str(detail)}, status_code=status)