docs: clarify host context integration paths

[stgomoyaa]

Description

Add a focused host-context decision guide for integrations that use full Directives, brief registry lines, or progressive loading.

• docs/usage/skill_chaining.md adds the six-row decision table, five-term glossary, progressive-disclosure callout, and explicit non-goals.
• docs/usage/README.md points the shared-patterns section to the new decision guide.
• docs/usage/agent_loops.md explains the SkillContext.execute() and prepare() boundary and updates the misleading code comment.
• CHANGELOG.md records the user-facing documentation update under [Unreleased].

This change was developed with AI assistance and was reviewed and tested locally.

Type of Change

• New Skill — new registry bundle under skills/
• 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
• CLI — skillware/cli.py, docs/usage/cli.md
• Examples — examples/*.py, examples/README.md
• Packaging — PyPI wheel, pyproject.toml, MANIFEST.in
• RFC / meta — templates, labels, CI, or large design doc

Checklist (all PRs)

• Linked GitHub issue (Closes #348)
• Scope matches the issue — no unrelated refactors
• python -m black --check . and flake8 pass locally
• pytest skills/ and pytest tests/ pass locally
• CHANGELOG.md updated under [Unreleased] for this user-facing documentation change
• examples/README.md updated if this PR adds, renames, or removes a runnable script
• Ran the documentation guards relevant to the changed usage pages
• Ran pytest tests/test_skill_docs.py when catalog Usage Examples or provider snippets changed

Evidence

$ .venv/bin/python -m black --check .
All done! 199 files would be left unchanged.

$ .venv/bin/python -m flake8 .

$ .venv/bin/python -m pytest skills/
369 passed, 1 skipped in 20.33s

$ .venv/bin/python -m pytest tests/
387 passed, 4 skipped in 34.74s

$ .venv/bin/python -m pytest tests/test_registry_docs.py tests/test_skill_docs.py
11 passed in 0.70s

Constitution and safety (skills only)

Not applicable; this PR changes documentation only.

Related Issues

Closes #348

[rosspeili]

Hey @stgomoyaa thanks for this, and welcome to Skillware <3

First, I would advice you to claim the issue by commenting on #348, so you can be assigned. This keeps PR reviews clean and focused, especially for good first issues.

Then I am happy to accept this PR as it is clean, adheres to repo standards and contributing guide, after you fix some minor nits:

• CHANGELOG placement: the [Docs]: Add minimal host context / integration-path guide (Directive vs brief vs prepare) #348 entry landed under [0.5.4] → Changed instead of [Unreleased] → Changed. Please move it up, CONTRIBUTING expects new entries under [Unreleased].
• Pre-existing (not [Docs]: Add minimal host context / integration-path guide (Directive vs brief vs prepare) #348) but nice to fix also: office/gmail_handler row sits outside the reference-scripts table in agent_loops.md.