feat: [ENG-1505] add context tree management to local web UI

[ncnthien]

• Tree browse with expand/collapse, file detail with markdown rendering
• File editing with save, version history with cursor-based pagination
• 3-panel layout (tree, detail, history) with collapsible panels
• Breadcrumb navigation, author timeline, folder metadata
• URL-based path/branch sync for bookmarking
• Remove auth guard for local web access

Summary

• Problem:
• Why it matters:
• What changed:
• What did NOT change (scope boundary):

Type of change

• Bug fix
• New feature
• Refactor (no behavior change)
• Documentation
• Test
• Chore (build, dependencies, CI)

Scope (select all touched areas)

• TUI / REPL
• Agent / Tools
• LLM Providers
• Server / Daemon
• Shared (constants, types, transport events)
• CLI Commands (oclif)
• Hub / Connectors
• Cloud Sync
• CI/CD / Infra

Linked issues

• Closes #
• Related #

Root cause (bug fixes only, otherwise write N/A)

• Root cause:
• Why this was not caught earlier:

Test plan

• Coverage added:
  • Unit test
  • Integration test
  • Manual verification only
• Test file(s):
• Key scenario(s) covered:

User-visible changes

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If none, write None.

Evidence

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• Failing test/log before + passing after
• Trace/log snippets
• Screenshot/recording

Checklist

• Tests added or updated and passing (npm test)
• Lint passes (npm run lint)
• Type check passes (npm run typecheck)
• Build succeeds (npm run build)
• Commits follow Conventional Commits format
• Documentation updated (if applicable)
• No breaking changes (or clearly documented above)
• Branch is up to date with main

Risks and mitigations

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• Risk:
  • Mitigation: