feat(kyberforge): add agent-audit skill (closes #11)

## Why

agent-author produces paired agent definition files (Claude Code .md +
Copilot .agent.md) but had no companion audit skill to validate them.
agent-audit fills that gap, giving the same structured PASS/FAIL report
that skill-audit provides for SKILL.md files.

## Implementation Notes

- validate.sh uses scope detection (walk up for plugin.json / .git) to
  locate the counterpart file and determine whether plugin-silently-ignored
  fields (hooks, mcpServers, permissionMode) should be flagged
- CC-only and silently-ignored field lists are read from
  references/field-inventory.md at runtime rather than hardcoded —
  provenance back to the research corpus; see ADR-0019
- Single-file invocation (pass either file, counterpart derived) chosen
  over directory or name+root — see ADR-0018
- 12 bats tests cover provider detection, scope detection, all FAIL paths,
  and clean-pair pass

## Impact

- kyberforge bumped to v1.1.2
- agent-author close step should be updated to reference agent-audit (#11)
- Provenance/sources chain check deferred to #60

ADR: docs/adr/0018-agent-audit-single-file-invocation.md
ADR: docs/adr/0019-agent-audit-field-inventory-reference.md
Refs: #11
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0147vXtL5sP6vorDdqXGJJU9

plugins/kyberforge/skills/agent-audit/tests/README.md

@@ -0,0 +1,33 @@
+# tests/
+
+Test files for scripts bundled with this skill.
+
+## When to add tests
+
+Add tests here when the skill has scripts in `scripts/` that are complex enough
+to break silently — validators, parsers, generators, anything with branching
+logic or edge cases. Test infrastructure (`.bats`, `*_test.*`, `test_*.sh`)
+belongs here, not in `scripts/`.
+
+## Dependencies
+
+Tests require [bats-support](https://github.com/bats-core/bats-support) and
+[bats-assert](https://github.com/bats-core/bats-assert). The test files load
+helpers from the repo root's `tests/test_helper/`.
+
+From the repo root:
+
+```bash
+git clone https://github.com/bats-core/bats-support tests/test_helper/bats-support
+git clone https://github.com/bats-core/bats-assert tests/test_helper/bats-assert
+```
+
+Run all tests for this skill (from the repo root):
+
+```bash
+bats <destination-dir>/agent-audit/tests/
+```
+
+## If no tests are needed
+
+Delete this README and the `tests/` directory entirely.