Add UX MVP CLI flows

[LiranCohen]

Summary

This is stacked on #184 (fix/install-wrapper-symlink-clobber) so the UX MVP diff stays separate from the wrapper/helper fixes already under review.

• add the UX MVP plan and implement first-run identity/session handling for local edge-run workflows
• add public-read clone fallback, repo context persistence, helper/session visibility, doctor/repair, and safer write guards
• improve PR, issue, repo role, moderation, and maintainer flows with inferred context, prompts, and authority summaries
• add $squash view snapshot schema coverage and broad focused/unit/e2e tests for the new UX paths

Verification

• bun run lint
• bun run build
• git diff --check
• bun test .spec.ts (1785 pass, 8 skip, 0 fail, 49 files)