docs: comprehensive README update

[fazxes]

Summary

• Updates README.md to accurately reflect the current repo structure after the major restructuring in session Open PR from previous session requires full review before merge #103
• Fixes stale stats (PRs: 30+ -> 155+, modules: 34 -> 23+7), adds missing sections (role selection, security-check operator), and aligns make targets, config, CLI commands, and architecture trees with reality

Changes

• Roles: 5 -> 6 operators (added security-check preflight description)
• Stats table: Added daemon sessions (100+), learnings (90+), split module count into product/framework
• Make targets: Replaced non-existent make review/overseer/strategist with actual targets (make test/dry-run/quick-test/clean)
• CLI: Added verify-cycle command
• Config: Updated blocked_paths (4 -> 8) and blocked_globs (3 -> 6) to match .nightshift.json.example
• Env vars: Added descriptions and two new vars (RECURSIVE_FORCE_ROLE, RECURSIVE_PIPELINE_CHECKPOINTS)
• New section: "How it picks what to do" explaining signal-driven role scoring
• Recursive/ tree: Added skills/ directory, annotations for each operator and sub-agent
• Guard rails: Added specifics (category weights, circuit breaker, truncation limits)
• Current frontier: Updated shipped list and open queue count (69 pending)

Test plan

• All changes are documentation-only (README.md)
• Verify all referenced paths exist in the repo
• Verify stats match live repo data