Support for project-specific patterns + skill for creating patterns for a repo

[sandst1]

Support for project-specific patterns + skill for creating patterns for a repo

Summary

• Adds a project-local pattern layer at /.oo/patterns/ that is resolved before user-global (~/.config/oo/patterns/) and built-in patterns, so repo-specific patterns can be checked in alongside the code they describe.
• Extends oo patterns to show both project and user pattern directories with labelled sections, falling back to "no patterns yet" only when both are empty.
• Adds project_patterns_dir() to src/init.rs (reusing the existing find_root walk) and load_project_patterns() / list_patterns_in() helpers in src/commands.rs.
• Updates docs/patterns.md to document the two-tier loading order.
• Adds integration tests asserting project patterns are listed, and that they override built-in patterns at runtime.
• Adds a Claude skill (.claude/skills/oo-learn-patterns/SKILL.md) that guides an agent to scan a repo's toolchain and scaffold .oo/patterns/*.toml files.

Checklist

• Tests written and passing (cargo test)
• Clippy clean (cargo clippy -- -D warnings)
• Formatted (cargo fmt --check)
• Coverage maintained (cargo tarpaulin --fail-under 70)
• Documentation updated if needed