Add project-mode create flow and top-level navbar links

[raphaeltm]

Summary

• Added top-level primary navigation links (Dashboard, Projects, Nodes, Settings) directly in the header via UserMenu so users no longer need to open the avatar menu for core navigation.
• Added project-oriented routes:
  • /projects (dashboard/project list view)
  • /projects/new (project-mode create flow)
• Reused the existing create flow for project mode by extending CreateWorkspace with a mode prop (workspace or project) to adjust labels/navigation copy.
• Updated RepoSelector so repository options appear on focus (true dropdown behavior without typing first).
• Added/updated unit tests for create flow behavior, top-level nav behavior, and stabilized one existing flaky warning assertion test.

Validation

• pnpm lint
• pnpm typecheck
• pnpm test
• Additional validation run (if applicable)
• Mobile and desktop verification notes added for UI changes

Additional validation notes:

• Ran targeted and full web test suites:
  • pnpm --filter @simple-agent-manager/web test -- tests/unit/pages/create-workspace.test.tsx tests/unit/components/user-menu.test.tsx
  • pnpm --filter @simple-agent-manager/web test
• Mobile viewport screenshot captured with Playwright CLI:
  • .codex/tmp/playwright-screenshots/landing-mobile.png

UI Compliance Checklist (Required for UI changes)

• Mobile-first layout verified
• Accessibility checks completed
• Shared UI components used or exception documented

Exceptions (If any)

• Scope: Authenticated route screenshot validation for /projects and /projects/new
• Rationale: Local auth bootstrap for protected routes is not configured in this environment; validated route/UI behavior via unit tests and mobile landing screenshot during dev-run.
• Expiration: Re-verify on a staging deployment with authenticated Playwright flow.

Agent Preflight (Required)

• Preflight completed before code changes

Classification

• external-api-change
• cross-component-change
• business-logic-change
• public-surface-change
• docs-sync-change
• security-sensitive-change
• ui-change
• infra-change

External References

N/A: No external API contract changes; implementation used existing repository code patterns.

Codebase Impact Analysis

• apps/web/src/App.tsx (new project routes)
• apps/web/src/pages/CreateWorkspace.tsx (project mode labels/navigation)
• apps/web/src/components/UserMenu.tsx (top-level nav links + retained profile dropdown)
• apps/web/src/components/RepoSelector.tsx (dropdown-on-focus repo selection)
• apps/web/tests/unit/pages/create-workspace.test.tsx
• apps/web/tests/unit/components/user-menu.test.tsx
• apps/web/tests/unit/components/agent-settings-section.test.tsx (stabilized existing assertion)

Documentation & Specs

• Updated task record: tasks/backlog/2026-02-18-project-creation-dropdowns-and-navbar-links.md
• No additional docs currently reference these frontend navbar/route details.

Constitution & Risk Check

• Checked constitution Principle XI (No Hardcoded Values): no internal URLs/timeouts/limits/identifiers were hardcoded in business logic.
• Key risk addressed: navigation discoverability and repo selection UX on create flow.
• Remaining risk: authenticated mobile visual verification should be repeated on staging with login flow.