feat(tui): include project directory name in terminal title

[F0Rextasy]

What

I reviewed the full diff; every tab showed only the session title so repos were indistinguishable, so the terminal title now appends the project directory name while the run-state separator keeps working.

Why

Fixes #12600

Testing

• bun test packages/coding-agent/test/terminal-title-state.test.ts (22 pass, 3 new: suffix appended, deduped when equal, fallback stays bare)
• bun --cwd=packages/coding-agent run check:types (pass)
• oxlint on both changed files (pass)

---

• bun check passes
• Tested locally
• CHANGELOG updated with the required attribution (if user-facing; internal issue fixes use issue links, external contributions add the PR link and contributor credit after creation)

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