refactor(mcp): split skill tool handler into its own module

[getappz]

Summary

• Move skill()'s search/load bodies out of mcp_server.rs into src/mcp_server/skill.rs, matching the one-file-per-tool convention already used by item.rs/claim.rs/comment.rs/handoff.rs/memory_tool.rs/review.rs/search.rs/artifact.rs/asset.rs/flare_docs.rs/flare_git.rs.
• No behavior change — bodies moved verbatim, skill() is now a thin self.skill_impl(req).await dispatch.

Salvaged from a review of stale branch task/29 (agentflare item #29, cancelled as superseded — its McpTool trait/registry port was dead code and the premise itself is superseded by this exact per-tool-module convention). This PR covers only the one genuinely reusable idea from that review: agentflare item #336.

Test plan

• cargo build — clean
• cargo fmt --check — clean
• cargo test --bin agentflare mcp_server — 126 passed, 0 failed (incl. skill_search_empty_query_is_invalid_params, skill_search_mode_rejects_unknown_value, skill_load_unknown_name_reports_not_found_with_search_hint)
• cargo clippy --workspace --all-features -- -D warnings — pre-existing daemon_autostart.rs dead-code errors confirmed present on plain master too, unrelated to this change

Summary by CodeRabbit

• New Features
  • Added skill search functionality with support for query matching modes and configurable result limits.
  • Added skill loading by name, including optional activation guidance and companion script details.
  • Improved error handling for missing, ambiguous, invalid, or unknown skill requests.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 51612057-d95e-49f3-8b49-942048c54abb

📥 Commits

Reviewing files that changed from the base of the PR and between 8a48eaf and 155b994.

📒 Files selected for processing (2)

• src/mcp_server.rs
• src/mcp_server/skill.rs

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📝 Walkthrough

Walkthrough

The MCP skill tool’s search and load dispatch is extracted from src/mcp_server.rs into src/mcp_server/skill.rs. The new handler preserves validation, registry operations, error mapping, JSON serialization, and optional activation-wrapper formatting.

Changes

Skill handler refactor

Layer / File(s)	Summary
Skill action implementation src/mcp_server/skill.rs	skill_impl handles search and load actions, including validation, registry queries, error mapping, JSON serialization, and optional activation-wrapper output.
Skill tool wiring src/mcp_server.rs	The new module is registered and the MCP skill tool delegates requests to skill_impl.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• getappz/agentflare#92: Introduces the skill registry and related skill search/load functionality used by this handler.
• getappz/agentflare#185: Consolidates the MCP skill endpoint around action-dispatched SkillRequest handling.
• getappz/agentflare#253: Establishes the pattern of splitting MCP tool implementations into dedicated modules.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: moving the skill tool handler into its own module.
Description check	✅ Passed	The PR includes a clear summary and test plan, covering the main change and validation steps.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch task/336

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