fix(types): make manifest.py clean under pyright strict

- log.die() typed NoReturn so pyright knows it terminates control flow
  (was returning the unreachable Die instance type).
- manifest.py: raw inputs typed object (not Any) and narrowed via a new
  _as_json_object helper that validates str keys and returns
  dict[str, object]. Eliminates the Unknown cascade through .get()
  calls under strict.
- _from_dict classmethods renamed to from_dict so cross-class
  construction (Bottle.from_dict from Manifest.from_json_obj, etc.)
  doesn't trip reportPrivateUsage.
- _SUPPORTED_RUNTIMES typed tuple[Runtime, ...] so the membership
  check narrows runtime_raw to Literal["runc", "runsc"] and the
  # type: ignore[assignment] is no longer needed.
- Bottle.env uses a typed _empty_str_dict factory; bare dict resolves
  to dict[Unknown, Unknown] under strict.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

claude_bottle/log.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import sys
+from typing import NoReturn
 
 
 def info(msg: str) -> None:
@@ -18,6 +19,6 @@ class Die(SystemExit):
     fatal exit from an unrelated SystemExit."""
 
 
-def die(msg: str) -> "Die":
+def die(msg: str) -> NoReturn:
     print(f"claude-bottle: error: {msg}", file=sys.stderr)
     raise Die(1)