feat(dashboard): add Harness tab to project settings with engine/model/iterations controls

[aaight]

Summary

Moves agent engine, model, and max iterations settings out of the General tab into a new dedicated Harness tab on the project detail page.

• New Harness tab — appears between General and Work, contains agent engine selector, engine settings fields, model picker, and max iterations input
• Cleaned-up General tab — now focuses on project metadata (name, repo, branches, budget, watchdog timeout, progress settings, run-link toggle)
• Shared update hook (use-project-update.ts) — both forms use the same useProjectUpdate hook ensuring identical cache invalidation (projects.getById + projects.listFull) and consistent Saving/Saved UX
• Partial-update safety — each form only sends the fields it owns; harness fields are never nulled by a General save and vice versa

Card: https://trello.com/c/69b5c90fb7742b3b26378776

Files Changed

• web/src/routes/projects/$projectId.tsx — adds 'harness' to Tab union, adds Harness tab button and panel
• web/src/components/projects/project-general-form.tsx — removes model, maxIterations, agentEngine, engineSettings fields; switches to shared hook
• web/src/components/projects/project-harness-form.tsx — new form component with engine/model/iterations/engine-settings fields
• web/src/components/projects/use-project-update.ts — new shared hook for projects.update mutation + cache invalidation

Test plan

• npm run build:web passes (zero type errors) ✅
• npm run typecheck passes ✅
• npm run lint passes ✅
• Open a project — Harness tab appears between General and Work
• Set engine/model/iterations in Harness tab, save, refresh — values persist
• Edit only General fields, save — engine/model/iterations in Harness remain unchanged
• Switch engines in Harness — ModelField and EngineSettingsFields respond correctly

🤖 Generated with Claude Code

🕵️ claude-code · claude-sonnet-4-6 · run details

[nhopeatall]

Summary

LGTM — Clean extraction of harness settings into a dedicated tab with a well-factored shared update hook.

The partial-update safety claim is verified: the backend projects.update endpoint uses optional/nullish fields, so each form only sends the fields it owns — neither form can overwrite the other's values. The shared useProjectUpdate hook correctly consolidates mutation logic and cache invalidation. CI is all green.

Minor observations (not worth blocking on):

• project-general-form.tsx still declares model, maxIterations, agentEngine, and engineSettings in its local Project interface despite no longer using them. Harmless since TypeScript allows extra properties, but could be trimmed for clarity.
• numericFieldDefault is duplicated across both form files. Could be shared, but with a 2-line function in only 2 files, it's not worth an extra import.

🕵️ claude-code · claude-opus-4-6 · run details