feat(skills): formalize agent coordination via beadboard-driver

We moved from ad-hoc task claims to a strictly defined 'Skill' system.

Triumphs:
- Implemented the 'beadboard-driver' skill, which encodes our project-specific coordination protocols (claim, reservation, handoff).
- This ensures that any AI operative (or human supervisor) can participate in the project lifecycle using a unified CLI-driven state machine.
- Decoupled high-level mission logic from low-level file mutations, allowing for easier agent skill composition in the future.

Raw Honest Moment:
Initially, we were just 'winging it' with manual status updates. Formalizing this into a skill was a necessary step to ensure our collaboration is repeatable and resilient to agent context swaps.

skills/beadboard-driver/references/failure-modes.md

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+# Failure Modes
+
+## `BD_NOT_FOUND`
+
+- Cause: `bd` missing from PATH.
+- Recovery: install beads CLI or add `bd` executable directory to PATH.
+
+## `BB_NOT_FOUND`
+
+- Cause: `BB_REPO` invalid or no `bb` command / cache / discovery hit.
+- Recovery:
+  - Set `BB_REPO` to BeadBoard repo root.
+  - Verify `bb.ps1` exists under `BB_REPO`.
+  - Retry preflight.
+
+## `NAME_GENERATION_EXHAUSTED`
+
+- Cause: all generated names collided with existing registry entries.
+- Recovery:
+  - increase retry count (`BB_NAME_MAX_RETRIES`),
+  - expand adjective/noun pools,
+  - retry generation.
+
+## Reservation Conflicts
+
+- `RESERVATION_CONFLICT`: active owner exists.
+- `RESERVATION_STALE_FOUND`: stale reservation exists; use takeover only when safe.
+- `RELEASE_FORBIDDEN`: non-owner attempted release.
+
+## Mail Lifecycle Errors
+
+- `UNKNOWN_SENDER` / `UNKNOWN_RECIPIENT`: register agents before send.
+- `ACK_FORBIDDEN`: only recipient may ack.
+- `MESSAGE_NOT_FOUND`: stale id or wrong message reference.
+
+## Policy Guardrails
+
+- Do not write `.beads/issues.jsonl` directly.
+- Do not close beads without verification evidence.
+- Do not bypass `BB_REPO` when it is set but invalid; fix it explicitly.