Add setup script file picker field (codex)

[numnx]

🧩 Task: Add setup script file picker field

Automated task PR opened by Code UX for T02.

📋 Summary

Sprint: Sprint 139 · Settings mcp and & custom container · Task: T02

Improve Settings so operators can configure HTTP MCP servers with clear guidance and choose a custom container setup script through a file-picker field.

📝 Full Task Prompt

## Objective
Make `cliWorkflow.containerSetupScriptPath` configurable through a file-picker field in Settings while keeping direct text entry available for advanced or relative paths.

## Scope
- `dashboard/src/v2/components/settings/panels/SettingsGeneralPanel.tsx`
- `dashboard/src/v2/components/settings/ProjectSettingsEditor.tsx`
- `dashboard/src/v2/lib/project-api.ts` `fetchLocalFiles` helper from T01
- Optional reusable component under `dashboard/src/v2/components/settings/` such as `LocalFilePickerField.tsx`
- `tests/dashboard/v2/settings-general-panel.test.tsx`
- `tests/dashboard/settings-page.test.tsx` or a focused new dashboard test if the older editor remains covered there
- `docs/dashboard/design-system-settings.md`

## Implementation Requirements
1. Build or extract a reusable file-picker field that combines the existing `TextInput` style with a `Browse` action, uses `fetchLocalFiles`, and shows directory navigation controls for parent/home/current typed path similar to `AddProjectModal.tsx` directory browsing.
2. Use the file picker for `cliWorkflow.containerSetupScriptPath` in `SettingsGeneralPanel.tsx`; when a file is selected, write its path through the existing immutable `update` recipe to `current.cliWorkflow.containerSetupScriptPath`.
3. Apply the same field to `ProjectSettingsEditor.tsx` for the legacy/project editor surface if that component remains rendered by tests or routes, while preserving the existing `containerImage`, cache, and Playwright browser controls.
4. Preserve manual typing for empty, relative, and absolute paths; the picker must not force a path to exist before saving because runtime still supports relative repo/root resolution.
5. Add dashboard tests that mock `fetchLocalFiles`, open the picker, navigate/select a file, verify `containerSetupScriptPath` updates, and verify an API error is announced without clearing the typed value.
6. Update `docs/dashboard/design-system-settings.md` with the file-picker accessibility contract for settings path fields.

## Constraints
- This task depends on T01 and must consume the `fetchLocalFiles` API/type contract produced there.
- Do not change settings schema, sanitizer defaults, or Docker runtime behavior.
- Do not remove manual text input or prevent relative paths such as `.code-ux/container/setup.sh`.
- Keep picker errors visible with `role="alert"` and loading/empty states visible without relying on animation.
- Avoid introducing new dependencies; use existing Preact, lucide-preact, and settings primitives.

## Verification
- Run `pnpm exec vitest run tests/dashboard/v2/settings-general-panel.test.tsx tests/dashboard/settings-page.test.tsx`.
- Run `pnpm run test:dashboard`.
- Run `pnpm run lint`.
- Success means selecting a file updates the setup script path, manual entry still works, picker failures are accessible, and existing settings tests pass.

✅ QA Review

⏳ QA review runs after this PR is opened. Check the task card in the dashboard for the outcome once it lands.

🤖 Model & Provider

Provider	Codex CLI
Model	gpt-5.5

⏱️ Timing

Started	2026-07-06 09:55:50 UTC
Finished	2026-07-06 10:00:47 UTC
Duration	4m 58s

📊 Token Usage

Metric	Value
Input tokens	70,981
Cached input tokens	1,165,696
Output tokens	10,359
Total tokens	1,247,036
Invocations	1
Tool calls	41
Active time	4m 34s

Included usage estimate (subscription/local login): $1.25

🌿 Branch Info

Base: feature/CODUX-139-settings-mcp-and-custom-container
Head: task/feature-codux-139-settings-mcp-and-custom-contai-t02-codex-mr91oht3

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🤖 Generated by Code UX