feat(static): embed labdb/public/* and serve from BridgeDispatch

Drops labdb's index.html / login.html / css / js into the binary via
embed.FS so the single 24 MB fivenode_go binary now ships both the
HTML/JS frontend AND the JSON API. No web server, no Apache,
no asset bundler.

  hbrtl_ext/labdb_static/
    public/                 mirror of fivenode/labdb/public/
    assets.go               //go:embed public + two PRG-callable
                            HB_FUNCs: LABDB_STATIC_FILE(cPath) returns
                            the bytes, LABDB_STATIC_MIME(cPath)
                            returns the Content-Type derived from
                            the resolved (not raw) extension so "/"
                            -> text/html, not application/octet-stream.

  app/bridge_server.prg
    BridgeDispatch now falls through to the static FS for any path
    that isn't /api/*. Missing assets get a 404 instead of being
    routed to the path-to-symbol dispatcher.

Verified:
  GET /                  -> 200 text/html, full index.html body
  GET /login.html        -> 200 text/html, 1850 bytes
  GET /css/app.css       -> 200 text/css
  GET /api/admin-stats   -> 200 JSON {devices:2,...} (still live PG)
  GET /nonexistent.html  -> 404 text/plain

Phase 1a complete: HTTP serves both the labdb frontend and the
real-data labdb API from one binary, end to end.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cmd/fnode/main.go

@@ -40,6 +40,7 @@ var defaultRTL = []string{
 	"fivenode_go/hbrtl_ext/pgrtl",
 	"fivenode_go/hbrtl_ext/dispatch",
 	"fivenode_go/hbrtl_ext/labdb_state",
+	"fivenode_go/hbrtl_ext/labdb_static",
 }
 
 func main() {