[Feat]: Loader validates manifest.name matches skill folder path (#101 Option A)

[rosspeili]

Feature Description

Implement Option A from #101: the canonical registry ID is category/skill_name derived from the skill folder path; manifest.yaml name must match.

Behavior

• On SkillLoader.load_skill(...), after resolving the skill directory and loading manifest.yaml, compute:

expected_id = f"{skill_dir.parent.name}/{skill_dir.name}"
actual = manifest.get("name", "")

• If actual != expected_id: warn in v1 (deprecation period) or fail once legacy skills are migrated (see migration issue).
• Inject or expose registry_id on the returned bundle (optional) so callers don't re-derive from YAML alone.

Also update

• templates/python_skill/manifest.yaml — name: "<category>/<skill_name>" placeholder
• CONTRIBUTING.md — one paragraph decision record (Option A); link [RFC]: Skill identity in manifest.yaml — composite name vs category + skill_name #101
• Tests in tests/test_loader.py for match, mismatch, and missing name

Out of scope

• Separate category + skill_name manifest fields (Option B)
• load_skill_by_id aliases ([Feat]: Implement Skill Library Mapping and Simplified Import Mechanism #12)

Rationale

Three identity sources today (folder path, CLI list ID, LLM tool name from manifest["name"]) still disagree for legacy skills (office/pdf_form_filler, defi/evm_tx_handler). #101 RFC should close with this as the v1 contract; loader validation prevents new drift and gives contributors a clear error at load time.

Implementation Idea

1. Add _expected_registry_id(resolved_path: Path) -> str in loader.py.
2. Call after YAML load; use warnings.warn(..., SkillwareIdentityWarning) initially.
3. Flip to ValueError or ImportError after migration issue merges.
4. Document registry ID vs provider tool name (slashes vs underscores) in docs/usage/agent_loops.md if not already complete.
5. Depends on / coordinates with legacy manifest migration issue.

Blocks: consistent example tool dispatch (#178); unblocks alias design (#12).
Related: #101 (decision), migration issue below.