Add app label to root header and auto-reload sexp templates in dev

Show current subdomain name (blog, cart, events, etc.) next to the site
title in the root header row. Remove the redundant second "cart" menu row
from cart overview and checkout error pages.

Add dev-mode hot-reload for sexp templates: track file mtimes and re-read
changed files per-request when RELOAD=true, so .sexp edits are picked up
without restarting services.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sexp/jinja_bridge.py

@@ -53,11 +53,49 @@ def load_sexp_dir(directory: str) -> None:
             register_components(f.read())
 
 
+# ---------------------------------------------------------------------------
+# Dev-mode auto-reload of sexp templates
+# ---------------------------------------------------------------------------
+
+_watched_dirs: list[str] = []
+_file_mtimes: dict[str, float] = {}
+
+
+def watch_sexp_dir(directory: str) -> None:
+    """Register a directory for dev-mode file watching."""
+    _watched_dirs.append(directory)
+    # Seed mtimes
+    for fp in sorted(
+        glob.glob(os.path.join(directory, "*.sexp"))
+        + glob.glob(os.path.join(directory, "*.sexpr"))
+    ):
+        _file_mtimes[fp] = os.path.getmtime(fp)
+
+
+def reload_if_changed() -> None:
+    """Re-read sexp files if any have changed on disk. Called per-request in dev."""
+    changed = False
+    for directory in _watched_dirs:
+        for fp in sorted(
+            glob.glob(os.path.join(directory, "*.sexp"))
+            + glob.glob(os.path.join(directory, "*.sexpr"))
+        ):
+            mtime = os.path.getmtime(fp)
+            if fp not in _file_mtimes or _file_mtimes[fp] != mtime:
+                _file_mtimes[fp] = mtime
+                changed = True
+    if changed:
+        _COMPONENT_ENV.clear()
+        for directory in _watched_dirs:
+            load_sexp_dir(directory)
+
+
 def load_service_components(service_dir: str) -> None:
     """Load service-specific s-expression components from {service_dir}/sexp/."""
     sexp_dir = os.path.join(service_dir, "sexp")
     if os.path.isdir(sexp_dir):
         load_sexp_dir(sexp_dir)
+        watch_sexp_dir(sexp_dir)
 
 
 def register_components(sexp_source: str) -> None: