fix: preserve active terminal across reconnects

[Lint111]

Summary

Preserve the active terminal across same-process SSE reconnects instead of clearing state and replaying terminal history.

Extracted from #173 as a focused lifecycle fix.

Behavior

• Add a stable serverStartedAt process epoch to both SSE init and /api/status.
• Treat an initial load, same-process reconnect, and changed server process as distinct cases.
• Reconcile authoritative session, cost, timer, subagent, and workflow metadata in place on reconnect.
• Preserve the active xterm instance, buffer, geometry, scroll position, input, and terminal caches.
• Persist available draft/input state and reload once when the server process changes.
• Ignore stale HTTP fallback responses and equal/older init snapshots.
• Drop terminal frames after a replacement page has been requested.
• Keep repository-viewer scope synchronized when a reconnect reveals a changed active working directory.

Commits

1. feat(server): identify init snapshots by process
2. fix(client): preserve terminal across reconnects

Verification

• npx vitest run test/server-init-lifecycle.test.ts - 7 tests passed
• npx vitest run test/sse-events.test.ts - 7 tests passed
• npm run check:lockfile
• npm run typecheck
• npm run lint
• npm run check:frontend-syntax
• npm run check:public-assets
• npm run format:check
• npm run build
• Playwright at a 390x844 touch viewport against the production bundle:
  • one newer snapshot reconciled in place
  • an immediate duplicate snapshot was ignored
  • zero app resets and zero session reselections
  • active session, xterm instance, buffer object, and terminal geometry remained identical

Scope

No terminal rendering, input parsing, gesture controls, shutdown behavior, or repository-browser implementation is included. Optional draft and repository-viewer hooks compose with their separate PRs without making them dependencies.

[Ark0N]

Hi Lior, closing this one as part of a cleanup of the seventeen PRs currently open from you. The full explanation is in #173, and I would rather you read that one than this note, because it is the honest version and it is not a dismissal of your work.

The short form: sixteen PRs opened in a single day, roughly 42,000 added lines in total, landing mostly on the same few files (nine touch app.js, eight touch terminal-ui.js), with five already conflicting against master and none carrying CI results. I cannot review that at the standard this codebase needs, and merging it at a lower standard would be worse than not merging it.

Going forward, please keep no more than three open PRs at a time, each one a single behavior change that stands on its own, with a test that fails on master and passes with the fix. #214 and #215, merged today, are good models.

If this particular change fixes something that genuinely annoys you in daily use, it is a good candidate to be the first one you reopen on its own, rebased on current master. I will review it properly.

Thanks for the effort you put in, and sorry to close it this way.