fix: send without waiting for mcp, drop the unknown key note, mic on aster serve

[Zfinix]

What changes

• The first message no longer waits for MCP servers. A session with no cached tool list held the first submit until every server connected, which could take up to the startup timeouts. The turn now starts at once, the footer says the tools join the next message, and they do once the connect lands. Cost: one prompt-cache miss on the second message, only in a folder with no cached tool list.
• aster key set and aster env set drop the "Nothing in Aster reads …" note. MCP servers, skills, and scripts read variables Aster does not list, so it was often wrong.
• The aster serve page gets the mic button. The server runs aster dictate per tab and relays its events. The page raises its own toast for errors, since it has no editor notification. The rebuilt page bundle in crates/aster-serve/ui/ is included.

Testing

• make check passes, as does the pre-commit hook on each commit.
• VS Code webview and host typecheck, and vitest passes (325 tests).
• aster serve was run in a scratch folder:
  • With an ElevenLabs key, a recording came back as text in the composer.
  • With no key, the toast showed the key message above the composer and the button reset.

The recording happens on the machine running aster serve, so a page opened from another device listens through the host's mic.

🤖 Generated with Claude Code