feat(params): parameterized skills with CLI/env overrides

[00200200]

Summary

• Add typed parameters frontmatter (string / int / boolean / choice) with schema validation and safe {{ name }} / $name substitution (stdlib only).
• Resolve values with CLI --param key=value > CINCH_PARAM_* env > defaults, prompting via questionary only for required unset params on a TTY without --yes.
• Apply substitution when compiling/wiring skill bodies (init + preview); strip the parameters block from dialect output.

Closes #14

Test plan

• uv run pytest
• uv run ruff check .
• uv run ruff format --check .
• Manual: cinch init ... --param framework=pytest against a skill with a parameters block

[github-actions]

👋 Thanks for opening this pull request, @00200200!

We're thrilled to have your contribution to cinch! Here is a quick checklist to help get your PR merged smoothly:

• Linked Issue: Issue reference detected in PR body. ✅
• Local Verification: Verify all checks pass locally using uv run pytest and uv run ruff check ..
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