feat(share): server-run tunnel, share UI, terms consent; v0.0.6 - #12

Summary

Release 0.0.6.

• Server-run share. The server starts and stops cloudflared itself (shelldeck/share.py), so a share keeps running until it's stopped (sd share stop, Stop sharing, or Ctrl+C in the sd share that started it). The 60s CLI lease is gone, and sd share attaches to a share that's already running.
• Share UI. A Share button and Share… palette entry open a dialog with the QR code, copy link and new link. A Sharing pill shows while a share runs. Any host browser can allow or deny a waiting device (toast, dialog or Devices); the first answer wins over the sd share prompt.
• Terms of sharing. Before the first share, the dialog (checkbox) and sd share ([y/N]) show the risks: you share at your own risk, keep links private, Cloudflare sees the traffic, and don't share from corporate or restricted networks. POST /api/share returns 409 terms_required until POST /api/share/terms is accepted. The consent is stored in <config>/share-consent (owner-only, like the password) and asked again when TERMS_VERSION is bumped.
• Groundwork for the phone app (the app itself isn't in this PR): server-side agent state, remote logins that don't take the one-device slot, /api/push Expo tokens, and the ?embed=1 single-terminal view.
• Docs: CHANGELOG, README, CLAUDE.md, version 0.0.6 and uv lock.

Test plan

• uv run ruff check
• uv run pytest -q: 62 passed, including new terms tests for the API and CLI
• Edge (playwright-cli): the Share dialog shows the terms, and Start sharing is disabled until the box is checked
• Real tunnel start and stop with cloudflared, after merge or on an RC