feat: complete registry migration + new sister playbook + Hydra standing instruction

- sync_artifacts.sh: read file extensions from registry (dynamic find predicate)
- install_all.sh: read all sister crate paths from registry (was missing agentic-time)
- CLAUDE.md: standing instruction for Hydra gradual planning updates
- docs/NEW-SISTER-PLAYBOOK.md: complete step-by-step guide for birthing a new sister
- Section 26: soft guardrail checks Hydra doc has sections for all sisters
- Section 41: now validates install_all.sh and sync_artifacts.sh reference registry

Author: omoshola-o

CLAUDE.md

@@ -0,0 +1,37 @@
+# Agentra Workspace — Claude Code Instructions
+
+## Sister Registry
+
+All sister automation reads from `docs/sisters-registry.json` (single source of truth).
+To add a new sister, follow `docs/NEW-SISTER-PLAYBOOK.md`.
+
+## Hydra Gradual Planning (IMPORTANT)
+
+`goals/hydra/HYDRA-GRADUAL-PLANNING.md` is a living document that captures lessons from every sister for the future Hydra orchestrator. **It must grow naturally as work happens.**
+
+When you complete any of the following types of work on a sister, update the relevant section in HYDRA-GRADUAL-PLANNING.md:
+
+- **New pattern or architecture** — add to "Patterns Hydra Should Inherit" under that sister
+- **Edge case discovered** — add to "Edge Cases Discovered" under that sister
+- **Hardening or safety fix** — add to the sister's section with Hydra implications
+- **Integration challenge solved** — add to "Integration Challenges" if it taught something reusable
+- **New invention or capability** — note which Hydra component benefits
+
+This is not a separate task. It's part of finishing the work. When you solve a hard problem, the last step is noting what Hydra can learn from it.
+
+The file lives in `goals/hydra/` (gitignored, private). If it doesn't exist locally, skip silently.
+
+## Commit Style
+
+- Never add "Co-Authored-By: Claude" to commits
+- Use conventional commit prefixes: `feat:`, `fix:`, `chore:`, `docs:`
+
+## Guardrails
+
+Before pushing, run:
+```bash
+bash scripts/check-canonical-consistency.sh
+bash scripts/check-command-surface.sh
+```
+
+The 29 pre-existing command-surface failures (undocumented MCP tools in codebase + vision) are known and not blocking.