feat(skills): add per-task skill spec auto-detection and injection

Replace external inject-spec.py hook with built-in zero-config skill
detection in codeagent-wrapper. The system auto-detects project type
from fingerprint files (go.mod, package.json, etc.), maps to installed
skills, and injects SKILL.md content directly into sub-agent prompts.

Key changes:
- Add DetectProjectSkills/ResolveSkillContent in executor/prompt.go
- Add Skills field to TaskSpec with parallel config parsing
- Add --skills CLI flag for explicit override
- Update /do SKILL.md Phase 4 with per-task skill examples
- Remove on-stop.py global hook (not needed)
- Replace inject-spec.py with no-op (detection now internal)
- Add 20 unit tests covering detection, resolution, budget, security

Security: path traversal protection via validSkillName regex,
16K char budget with tag overhead accounting, CRLF normalization.

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

config.json

@@ -145,6 +145,24 @@
           }
         }
       ]
+    },
+    "claudekit": {
+      "enabled": false,
+      "description": "ClaudeKit workflow: skills/do + global hooks (pre-bash, inject-spec, log-prompt, on-stop)",
+      "operations": [
+        {
+          "type": "copy_dir",
+          "source": "skills/do",
+          "target": "skills/do",
+          "description": "Install do skill with 5-phase workflow"
+        },
+        {
+          "type": "copy_dir",
+          "source": "hooks",
+          "target": "hooks",
+          "description": "Install global hooks (pre-bash, inject-spec, log-prompt, on-stop)"
+        }
+      ]
     }
   }
 }