feat(web): serve the interface at / — /v3 kept as a legacy alias

The user-visible URL no longer carries the interface version: the pages
blueprint is now registered un-prefixed (primary) AND at /v3 (second
registration, name='pages_v3_legacy'), so:

- http://<device>/ serves the interface directly (the old @app.route('/')
  redirect is removed — the blueprint's own index takes its place)
- every existing /v3/... bookmark and all the hardcoded /v3/partials/...
  fetches in templates/JS keep working verbatim through the alias mount —
  zero template/JS churn, zero broken links
- url_for('pages_v3.*') resolves against the primary registration, so all
  server-side redirects (captive portal detection endpoints) now emit
  un-prefixed URLs
- the AP-mode captive-portal allowlist learned the un-prefixed page paths
  (/setup, /partials/, /settings/, /plugin-ui/) so setup-mode requests
  don't redirect-loop
- /api/v3 and the templates/v3, static/v3 directories are deliberately
  untouched (internal, invisible to users; owner-confirmed scope)

Validation: dual registration mechanics tested against real Flask (test
client): /, /v3, /v3/ redirect, partials and /setup reachable on both
mounts, url_for yields un-prefixed paths; py_compile passes.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEZK1P1Q1fu5pcuVrkrCFZ

web_interface/app.py

@@ -176,7 +176,12 @@ except Exception as _hm_err:  # pragma: no cover - defensive startup guard
         "Could not enable plugin health/metrics for web UI: %s", _hm_err
     )
 
-app.register_blueprint(pages_v3, url_prefix='/v3')
+# Pages are served un-prefixed (the interface lives at /); the /v3 mount is a
+# legacy alias kept so existing bookmarks and the hardcoded /v3/partials/...
+# fetches in templates/JS keep working unchanged. url_for('pages_v3.*')
+# resolves against the primary (un-prefixed) registration.
+app.register_blueprint(pages_v3, url_prefix='')
+app.register_blueprint(pages_v3, url_prefix='/v3', name='pages_v3_legacy')
 app.register_blueprint(api_v3, url_prefix='/api/v3')
 
 # Route to serve plugin asset files (registered on main app, not blueprint, for /assets/... path)
@@ -407,7 +412,11 @@ def captive_portal_redirect():
     
     # List of paths that should NOT be redirected (allow normal operation)
     allowed_paths = [
-        '/v3',  # Main interface and all sub-paths (includes /v3/setup)
+        '/v3',  # Legacy-prefixed interface and all sub-paths
+        '/setup',  # Captive setup page itself (un-prefixed mount)
+        '/partials/',  # HTMX partials (un-prefixed mount)
+        '/settings/',  # Settings search index (un-prefixed mount)
+        '/plugin-ui/',  # Plugin-provided web UI assets (un-prefixed mount)
         '/api/v3/',  # All API endpoints
         '/static/',  # Static files (CSS, JS, images)
         '/hotspot-detect.html',  # iOS/macOS detection
@@ -799,11 +808,8 @@ if limiter:
     limiter.limit("200 per minute")(stream_display)
     limiter.limit("200 per minute")(stream_logs)
 
-# Main route - redirect to v3 interface as default
-@app.route('/')
-def index():
-    """Redirect to v3 interface"""
-    return redirect(url_for('pages_v3.index'))
+# The pages blueprint's index now serves '/' directly (see the un-prefixed
+# blueprint registration above), so no redirect route is needed here.
 
 @app.route('/favicon.ico')
 def favicon():

web_interface/templates/v3/captive_setup.html

@@ -87,7 +87,7 @@ select:focus,input:focus{outline:none;border-color:#3b82f6;box-shadow:0 0 0 3px
 </div>
 
 <div class="footer">
-  <a href="/v3">Open Full Interface</a>
+  <a href="/">Open Full Interface</a>
 </div>
 
 <script>