fix(integrations): keep auto-managed Hindsight daemons working on Python 3.14 hosts

[r266-tech]

Summary

Fixes #2783 by making auto-managed uvx daemon launches default to Python 3.13 while the current LiteLLM/PyO3 dependency chain cannot build on Python 3.14.

• applies the compatible interpreter to Claude Code, Codex, Cursor, and Cursor CLI managed uvx launches
• preserves any non-blank user-provided UV_PYTHON override
• leaves embedPackagePath development installs on their existing uv run --directory path
• propagates the same environment through hindsight-embed to its nested hindsight-api uvx fallback

Cursor has no detached prestart path: its sessionStart hook enters _ensure_daemon_running(), and both profile creation and daemon startup already go through the updated _run_embed() path.

Testing

• Claude Code daemon tests: 5 passed
• Codex daemon tests: 5 passed
• Cursor daemon tests: 11 passed
• Cursor CLI daemon tests: 5 passed
• nested hindsight-embed environment tests: 2 passed
• full Codex integration suite: 95 passed
• full Cursor integration suite: 85 passed, 4 skipped
• full Cursor CLI integration suite: 92 passed
• Ruff check/format and git diff --check passed for the changed files

The full Claude Code suite reached 203 passed with one unrelated existing working-directory permission test failing in this macOS cron environment; the focused daemon tests are green.