feat: add architecture-colocate-contexts rule

[nouamanecodes]

Problem

The existing rules cover component composition and performance optimization well, but there's no guidance on where context files should live in a codebase. This leads to a common antipattern: dumping all contexts into a top-level src/contexts/ folder regardless of scope.

When contexts are scattered away from the components that use them:

• Debugging requires jumping between distant directories
• Moving a feature means updating imports across the codebase
• It's unclear which contexts are feature-scoped vs app-wide

Solution

This adds a new architecture-colocate-contexts rule that recommends placing context definitions adjacent to the components that consume them.

The rule covers:

• File structure pattern (types.ts, provider.tsx, index.ts)
• When to co-locate vs when to use a shared location
• Integration with the existing { state, actions, meta } context interface pattern

Example

Instead of:

src/contexts/ComposerContext.ts
src/components/Composer/Input.tsx

Co-locate:

src/components/Composer/context/types.ts
src/components/Composer/context/provider.tsx
src/components/Composer/context/index.ts
src/components/Composer/Input.tsx

This complements the composition-patterns skill by providing the structural container for those patterns.