feat: smooth ComfyUI in-place update flow (#557)

[Kosinkadink]

Closes #557.

Collapses the multi-step in-place update UX into a single confirm dialog and an auto-launch chain.

Before

1. Click the title-bar update pill → opens Settings → ComfyUI Settings → Update tab.
2. Click "Update Now".
3. Generic "instance is running, would you like to stop it" prompt — does not mention the update.
4. "Update from X to Y?" confirm dialog.
5. Update progress modal.
6. "Done" → back to the Update tab → user must manually click "Start ComfyUI".

After

1. Click the title-bar update pill → single confirm dialog: "ComfyUI is currently running and will be restarted to apply this update." followed by the existing release-notes / version body.
2. Confirm → ProgressModal runs stopComfyUI → update-comfyui → launch in one continuous view, ending in the new ComfyUI window opening automatically.

When the install was already stopped at confirm time, the restart-notice line and the auto-launch chain are skipped — the flow is just confirm → update → return to Update tab, identical to today.

Changes

• src/renderer/src/composables/useDeepLinkRouter.ts — when the title-bar pill fires panel-trigger-overlay { kind: 'install-update' }, open the Settings overlay with autoAction: 'update-comfyui' so the embedded DetailModal auto-runs the update action on mount. The Update tab still mounts behind the dialog so a cancel returns the user to the surface that shows release notes / channel info.
• src/renderer/src/views/DetailModal.vue:
  • Skip the generic actionGuard.checkBeforeAction "instance is running, stop it?" prompt for update-comfyui (mirroring the existing migrate-to-standalone exemption).
  • When the install is running, prepend standalone.updateRestartNotice to the action's existing confirm.message so a single dialog covers both stop + update.
  • In the showProgress branch, when update-comfyui is invoked while running, build an apiCall that chains stopComfyUI → wait-for-stopped → update-comfyui → launch. Mirrors the existing synthetic restart action's chained apiCall. triggersInstanceStart is set so PanelApp.handleShowProgress installs the chooser-host close-on-instance-started subscription for the post-update launch.
• locales/en.json — new standalone.updateRestartNotice string.
• src/renderer/src/panel/PanelApp.test.ts — extend the install-update payload test to assert that DetailModal receives auto-action="update-comfyui". Stub template now exposes autoAction as a data-auto-action attribute.

Verification

• pnpm run typecheck ✅
• pnpm run lint ✅
• pnpm run test ✅ (937 / 937)
• pnpm run build ✅