Add local-mode workspace, ZIP import/export, and richer pin/ADC/serial sims

Boot:
- Editor now picks local vs server mode based on URL flag, sign-in
  state, and a stale local-mode flag. Signed-in users are no longer
  bounced to IndexedDB if they had previously clicked "Use locally".

Local mode:
- New LocalWorkspaceClient (src/static/local-workspace.js) with
  pluggable IndexedDB and File System Access backends. Picked folder
  handles persist across reloads with a Reconnect button when the
  permission lapses.
- Static-only host: scripts/serve_static_editor.py serves src/static/
  with COOP/COEP so SharedArrayBuffer-backed sims keep working.
- Bundled MicroPython stubs ship under src/static/bundled-lib/ for
  static hosting; FastAPI also exposes them at /api/public/lib-bundle.

Workspace import / export:
- Zero-dep ZIP encoder + reader (STORE + DEFLATE via
  DecompressionStream). Export/Import buttons in the workspace badge
  work in both local and server modes; imports are confined to code/.

Pin / ADC / Serial simulation:
- machine.py grows ADC, UART, expanded Pin, and PWM mocks, all driven
  by SharedArrayBuffer when cross-origin isolated and falling back to
  postMessage + [pin-out] stdout markers otherwise — pins, ADC slider,
  and serial input now keep working over plain HTTP / LAN-IP origins.
- NeoPixel pins are claimed via a [pin-claim] marker and dropped from
  the Pins panel so the data line doesn't flicker per write().
- New demos: adc_slider_demo.py, pin_demo.py, serial_demo.py.

Lib layout:
- Single source of truth at repo lib/; workspace/lib/ caching layer
  removed and the directory deleted. Filesystem service reads stubs
  directly from PROJECT_ROOT/lib.

UI:
- Home page slimmed to "Sign in" + "Use locally" with optional editor
  / manage-users links. Admin user/invite UI moved to /users.
- Workspace badge gains storage indicator, Folder…/Reconnect, Export,
  Import, and Exit controls.
- Mobile-friendly tweaks: safer-area padding, larger touch targets,
  iOS-zoom-proof serial input, file-tree highlight fix.

Tests:
- test_auth.py patches PROJECT_ROOT for the lib-shared test so the
  repo-root lib refactor stays green. test_api.py asserts the new
  "LED Editor" branding.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/editor_app/services/user_workspace.py

@@ -16,22 +16,6 @@ _CANONICAL_DEMO_FILENAMES = (
 )
 
 
-def ensure_workspace_lib(workspace_root: Path | None = None) -> None:
-    """Copy shipped MicroPython stubs from the repo into WORKSPACE_ROOT/lib when each file is absent."""
-    dst_root = (workspace_root or config.WORKSPACE_ROOT).resolve() / "lib"
-    dst_root.mkdir(parents=True, exist_ok=True)
-    src_root = config.PROJECT_ROOT.resolve() / "lib"
-    if not src_root.is_dir():
-        return
-    for src in sorted(src_root.glob("*.py")):
-        if not src.is_file():
-            continue
-        dst = dst_root / src.name
-        if dst.exists():
-            continue
-        shutil.copy2(src, dst)
-
-
 def safe_workspace_leaf(username: str, user_id: int) -> str:
     base = re.sub(r"[^a-zA-Z0-9._-]+", "-", username.strip()).strip("-").lower() or "user"
     return f"{base}-{user_id}"