fix(ui): sub-path routing and API proxy for /magpie/ base URL

- spa_server.py: strip /magpie prefix before API check and file lookup;
  all HTTP methods call _normalise_path() first so /magpie/api/v1/* proxies
  correctly and /magpie/assets/* resolve against the dist root
- manage.sh: pass --base /magpie to spa_server.py so the handler knows
  the deployment prefix
- main.ts: pass import.meta.env.BASE_URL to createWebHistory so Vue Router
  strips the /magpie prefix before matching routes

Without these fixes, assets returned index.html (MIME type error), API
calls returned HTML instead of JSON (stats.posts undefined), and router
routes never matched (matched: []).

Closes: #12

frontend/src/main.ts

@@ -12,7 +12,7 @@ import OpportunitiesView from './components/OpportunitiesView.vue'
 import SignalsView from './components/SignalsView.vue'
 
 const router = createRouter({
-  history: createWebHistory(),
+  history: createWebHistory(import.meta.env.BASE_URL),
   routes: [
     { path: '/', redirect: '/signals' },
     { path: '/signals', component: SignalsView },

manage.sh

@@ -85,7 +85,7 @@ _start_web() {
     if [[ -f "frontend/dist/index.html" ]]; then
         info "Starting web on :${WEB_PORT} (static dist — production mode)..."
         conda run --no-capture-output -n "$CONDA_ENV" \
-            python scripts/spa_server.py --port "$WEB_PORT" --directory frontend/dist >> "$LOG_WEB" 2>&1 &
+            python scripts/spa_server.py --port "$WEB_PORT" --directory frontend/dist --base /magpie >> "$LOG_WEB" 2>&1 &
     else
         info "Starting web on :${WEB_PORT} (Vite dev server — no dist found)..."
         cd frontend
@@ -266,7 +266,7 @@ case "$cmd" in
     # In production, Caddy proxies menagerie.circuitforge.tech/magpie* → this port.
     info "Serving pre-built frontend on :${WEB_PORT} (SPA fallback enabled)..."
     conda run --no-capture-output -n "$CONDA_ENV" \
-        python scripts/spa_server.py --port "$WEB_PORT" --directory frontend/dist >> "$LOG_WEB" 2>&1 &
+        python scripts/spa_server.py --port "$WEB_PORT" --directory frontend/dist --base /magpie >> "$LOG_WEB" 2>&1 &
     echo $! > "$PID_WEB"
     ok "Static server up → http://localhost:${WEB_PORT}"
     ;;

scripts/spa_server.py

@@ -20,6 +20,18 @@ from http.server import HTTPServer, SimpleHTTPRequestHandler
 
 class SPAHandler(SimpleHTTPRequestHandler):
     api_port: int = 8532
+    base_prefix: str = ""  # e.g. "/magpie" — stripped before file lookup
+
+    # ------------------------------------------------------------------ #
+    # Path helpers
+    # ------------------------------------------------------------------ #
+
+    def _strip_base(self, path: str) -> str:
+        """Remove the base prefix so file lookup works against the dist root."""
+        p = path.split("?", 1)[0].split("#", 1)[0]
+        if self.base_prefix and p.startswith(self.base_prefix):
+            path = path[len(self.base_prefix):]
+        return path or "/"
 
     # ------------------------------------------------------------------ #
     # API proxy
@@ -51,11 +63,16 @@ class SPAHandler(SimpleHTTPRequestHandler):
     # Request dispatch
     # ------------------------------------------------------------------ #
 
+    def _normalise_path(self) -> None:
+        """Strip base prefix so all subsequent checks work on bare /api/ or /asset paths."""
+        self.path = self._strip_base(self.path)
+
     def _is_api(self) -> bool:
         path = self.path.split("?", 1)[0]
         return path.startswith("/api/")
 
     def do_GET(self) -> None:
+        self._normalise_path()
         if self._is_api():
             self._proxy_api()
             return
@@ -65,24 +82,28 @@ class SPAHandler(SimpleHTTPRequestHandler):
         super().do_GET()
 
     def do_POST(self) -> None:
+        self._normalise_path()
         if self._is_api():
             self._proxy_api()
             return
         self.send_error(405, "Method Not Allowed")
 
     def do_PUT(self) -> None:
+        self._normalise_path()
         if self._is_api():
             self._proxy_api()
             return
         self.send_error(405, "Method Not Allowed")
 
     def do_PATCH(self) -> None:
+        self._normalise_path()
         if self._is_api():
             self._proxy_api()
             return
         self.send_error(405, "Method Not Allowed")
 
     def do_DELETE(self) -> None:
+        self._normalise_path()
         if self._is_api():
             self._proxy_api()
             return
@@ -98,9 +119,11 @@ def main() -> None:
     parser.add_argument("--port", type=int, default=8531)
     parser.add_argument("--directory", default="frontend/dist")
     parser.add_argument("--api-port", type=int, default=8532)
+    parser.add_argument("--base", default="", help="URL base prefix to strip (e.g. /magpie)")
     args = parser.parse_args()
 
     SPAHandler.api_port = args.api_port
+    SPAHandler.base_prefix = args.base.rstrip("/")
     os.chdir(args.directory)
     server = HTTPServer(("", args.port), SPAHandler)
     print(