feat(chat): paginate history and support Droid SDK 0.10 - #22

Summary

• Replace JSONL-first chat history with official daemon cursor pagination, automatic earlier-page loading, a bounded reading window, and full-history export. Preserve explicit Process mode and on-demand original operation evidence, without silent daemon-to-Process fallback.
• Upgrade @factory/droid-sdk from 0.9.1 to 0.10.0. Use object transports, support Script batch and RecommendMission permissions, and adapt workspace/custom-model APIs.
• Keep ordinary compaction in place without replacing its session lease or resetting counters. Route /handoff explicitly to a successor and adopt Spec handoffs only from the documented planning-session event.
• Preserve required bounded-load and IDE compatibility patches. Remove unused string transport catalog interception. Update architecture, design, status, and remaining verification gaps.

Validation

• pnpm run typecheck and pnpm run lint:budgets: passed.
• SDK affected tests: 14 files, 570 tests passed.
• Pagination targeted tests: 23 files, 178 tests passed; affected recovery follow-up: 80 passed.
• Real daemon 1.2.0 pagination: 121 pages / 12,090 raw messages matched IDs and order; existing cursors remained valid after appended messages.
• Final package:vsix + verify:vsix at 73746a85: passed, 171 entries including bundled externals and extension entry loading.
• VSIX SHA256: 4430ed72279eb1642a33a8634e8f5d824c0a510dc940b0637923ebd3f6d1c04e.

Boundaries

• No paid model calls, daemon restart, or new browser acceptance run. The new Host paging UI and real compaction/rewind transitions still need user acceptance; no screenshot is presented as proof.
• The earlier pagination-only trial package was installed in Microsoft VS Code. The SDK-upgraded package has not been installed.
• Version remains 0.8.20 for local validation. This PR does not create a release, tag, marketplace publication, or automatic installation.
• Merge is authorized after required CI passes.