Complete the TypeScript workspace and standalone runtime bootstrap

[codeacme17]

Summary

• compose the loopback health server, Vite placeholder Git Surface, and concrete Standalone Host Adapter behind one launcher runtime
• make npm run dev print both loopback URLs and shut down the Host Connection and both listeners cleanly
• add a reusable temporary Git Repository fixture plus executable unit, contract, integration, and end-to-end test layers
• enforce that the browser UI cannot import Node filesystem or child-process modules
• complete the required workspace package entries, lockfile metadata, and bootstrap documentation

Acceptance criteria

• a clean checkout installs with npm ci, type-checks, tests, and builds using documented commands
• npm run dev starts the placeholder Git Surface through the Standalone Host Adapter
• npm test executes unit, contract, integration, and end-to-end tests
• the Repository Engine remains the planned session interface and contains no Git behavior
• the UI lint configuration rejects Node filesystem and child-process imports
• no Tauri dependency, Codex DOM selector, Git discovery, or Git mutation is introduced
• composition roots stay thin and tests observe public seams without internal mocks

Verification

• npm ci
• npm run format:check
• npm run lint
• npm run typecheck
• npm test — 5 test files and 5 tests passed
• npm run build
• focused contract, integration, server, UI, and standalone e2e runs
• UI restricted-import smoke check rejects node:fs
• real npm run dev smoke: health JSON and placeholder HTML both returned over loopback; SIGINT exited cleanly
• startup-failure and normal-close probes confirmed listener teardown
• two-axis review: Standards 0 findings; Spec 0 findings
• PR preflight was skipped by explicit maintainer decision

Dependency state

#2 landed in PR #22 and the dependency is satisfied. This PR has no remaining hard dependency and unblocks #4, #5, and #6.

The final diff contains 410 additions and 20 deletions across focused runtime, adapter, test, configuration, lockfile, and documentation files.

Scope

This PR completes bootstrap behavior only. It does not add Git product behavior, Codex injection, packaging, or product styling.

Known out-of-scope defects

No known pre-existing defects were found in the touched bootstrap paths.

Planned capabilities remain explicitly out of scope and tracked by #4 for Host Adapters, #5 for the versioned protocol and security boundary, and #6 for Repository and Worktree discovery.

Closes #3.