fix: address Copilot review on release/3.3.2

Non-ASCII glyphs (regression of the #681 class of Windows UnicodeEncodeError):
- mempalace/cli.py: "✗" → "ERROR:", "⚠" → "WARNING:", em dash → "-"
- mempalace/sweeper.py: "⚠" → "WARNING:"

Backend arg validation:
- mempalace/backends/chroma.py: `_normalize_get_collection_args` now
  raises TypeError on unexpected trailing positional args instead of
  silently dropping them — surfaces call-site bugs early.

Docs site:
- website/.vitepress/config.mts: gate Google Analytics scripts behind
  MEMPALACE_DOCS_GA_ID env var (default off). Self-hosters no longer
  get GA injected unconditionally.

Landing page SPA hygiene:
- website/.vitepress/theme/landing/useLandingEffects.js: collect all
  IntersectionObserver disconnects and removeEventListener thunks in a
  shared `cleanups` registry; drain it in `onBeforeUnmount` so observers
  and form/replay listeners don't leak across SPA navigations.

mempalace/backends/chroma.py

@@ -615,6 +615,8 @@ def _normalize_get_collection_args(args, kwargs):
         create = kwargs.pop("create", False)
         if rest:
             create = rest.pop(0)
+        if rest:
+            raise TypeError(f"unexpected positional args: {rest!r}")
         if kwargs:
             raise TypeError(f"unexpected kwargs: {sorted(kwargs)}")
         return (