refactor: remove terminal MCP, Playwright, and commands infrastructure

- Remove terminal/tmux MCP from voice LLM - it now only uses agent-control MCP
- Remove Playwright MCP auto-injection from Claude and Codex agents
- Remove commands state from session, store, and UI
- Remove present_artifact tool and guidelines from voice prompt
- Update agent-prompt.md examples to focus on agents instead of commands
- Remove @huggingface/transformers dependency and test scripts
- Add expandTilde utility to utils/path.ts

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.tasks/7ddb69c7.md

@@ -1,7 +1,7 @@
 ---
 id: 7ddb69c7
 title: Remove auto-injected MCPs (Playwright, etc) - make user-configured
-status: open
+status: done
 deps: []
 created: 2026-01-08T16:17:08.670Z
 ---