feat(web): set daemon settings per daemon, with batch apply

[futrime]

Summary

This is unit 8 of the multi-daemon and notifications batch: it splits Settings and makes the daemon side of it per daemon.

• Two groups in the nav. App holds Themes, plus Daemons and Notifications. Those two are optional pages from unit 9 and appear only once their modules import. Daemon holds General, Accounts, Fallback, Runtimes, Backup, Workspace and Usage.
• Daemon selector (data-hmz="settings-daemon").
  • It lists GET /api/daemons, and shows only Local when that endpoint is absent.
  • It defaults to the current daemon (api.daemon() when unit 6 provides it, else local).
  • It changes only which daemon these pages use: requests go to /d/<name>/api/..., or to plain /api/... for the daemon the page is on.
  • It is kept in the address as ?daemon=<name>, and the nav links carry it.
  • Shared helpers now take that prefix: readBackends(workspace, from) in pickers.js and pathPicker({from}) in paths.js. So the agent, place and path pickers also read the picked daemon.
• Batch apply (data-hmz="batch-apply"). It opens a dialog of the other daemons with All, POSTs the page's payload to each daemon ticked, and shows each daemon's result: Applied, or the refusal's sentence.
  • General sends the form as it stands.
  • Backup sends every target and the defaults.
  • Fallback sends each step, and Runtimes each runtime with replace: true. Both overwrite or add, and never remove anything.
  • Accounts: the button is disabled, marked "Secrets stay put".
  • Workspace and Usage have no button.
• Phone-width CSS is in a /* settings daemons */ block.
• docs/user/web.md is updated.

Test plan

• tests/integration/test_web_settings_daemons.py runs in chromium and webkit. It covers the grouping, the selector scoping reads and writes, ?daemon= in the address, batch apply POSTing to each daemon ticked with its result, accounts disabled, and phone width.
• Every tests/integration/test_web_*.py passes, including the settings tests in test_web_page.py.
• uv run pytest tests/unit passes.
• Pre-commit passes, except pyright's existing Linux-only errors on macOS.
• Live hmz web check: a Playwright script with routed fake daemons, screenshots at full width and at phone width.

🤖 Generated with Claude Code

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[futrime]

Landed together in #385.