feat(registry): improve manifest short_description for agent routing (#355)

[ump45nose]

Description

Improve every bundled skill's manifest.yaml short_description so agents using SkillContext(mode="brief") can route accurately and deterministically:

• Ensure each short_description explicitly states what the skill does and when to use it (trigger context).
• Keep length concise and well under the 160-character budget (recommended 80–120 chars).
• Avoid implementation noise (e.g. drop model names, "using Claude", etc.).
• Bump patch version for all 17 updated skills and align catalog table versions in docs/skills/README.md.
• Expand CONTRIBUTING.md specification for short_description agent routing.
• Add test_manifests_have_valid_short_descriptions guard in tests/test_registry_docs.py to enforce presence and length constraints (<= 160 chars).

Closes #355.

Type of Change

• Skill Upgrade — changes to an existing skill under skills/
• Bug Fix — incorrect runtime or framework behavior
• Documentation — docs, README, CONTRIBUTING only
• Framework Feature — skillware/core/ loader, env, adapters

Checklist (all PRs)

• Linked GitHub issue (Closes #355)
• Scope matches the issue — no unrelated refactors
• python -m black --check . and flake8 pass locally
• pytest tests/test_registry_docs.py and pytest tests/test_context_and_chains_integration.py pass locally
• Ran pytest tests/test_registry_docs.py when skills, examples index, or agent-loops matrix changed

New or updated skill

Bundle and metadata

• Skill at skills/<category>/<skill_name>/
• manifest.yaml: short_description updated, patch version bumped

Validation

• Tested with uv run --extra dev --extra gemini pytest tests/test_registry_docs.py tests/test_context_and_chains_integration.py (39 passed, 1 skipped).
• Verified uv run --extra dev black --check . and uv run --extra dev flake8 passed with 0 errors.

Drafted with AI assistance; reviewed diff and ran local test suite before submission.

[rosspeili]

Hey @ump45nose, please claim issues before workign on them, simply by commenting on the issue. This is important, and have been a review note in your previous PR. At the same time there is an open PR on this that is pending ammendment of review. I will give them priority, and consider yours if they fail to respond or stail for too long. Thanks <3