feat(agent): add skills system with profile integration (#21)

* chore(deps): add yaml package for skill parsing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* feat(agent): add skills system

Implement a skills system inspired by moltbot's approach:

- Skills are markdown files (SKILL.md) with YAML frontmatter
- Multi-source loading with precedence: bundled < user < workspace
- Eligibility filtering based on platform, binaries, and env vars
- Skills are automatically included in agent system prompt
- New AgentOptions: enableSkills, skillsBaseDir, extraSkillDirs

Includes two bundled skills:
- commit: Git commit helper with conventional commit guidelines
- code-review: Code review checklist and best practices

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* refactor(skills): use profile-based skills instead of workspace

Change skill loading from workspace-based (.skills/) to profile-based:
- Skills now load from ~/.super-multica/agent-profiles/<profileId>/skills/
- Remove workspace and user skill sources
- Simplify to only bundled and profile sources
- Profile skills have higher precedence than bundled

This is more appropriate for non-coding agents where skills are
associated with agent identity rather than working directory.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -53,6 +53,7 @@
     "socket.io-client": "^4.8.3",
     "turndown": "^7.2.2",
     "undici": "^7.19.2",
-    "uuid": "^13.0.0"
+    "uuid": "^13.0.0",
+    "yaml": "^2.8.2"
   }
 }