[FEATURE] Support file content pattern for auto-loading Claude Rules

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

In our projects, we have specific guidelines about some of our dependencies, such as how to write zod schemas.

Currently, .claude/rules are loaded on demand based on file paths (frontmatter setting).

However, dependencies may be used in any file and are valid throughout the project. But I don't want to pollute CLAUDE.md context with these rules

Proposed Solution

Frontmatter supporting regex based on file content:

patterns:
  - "/from \"zod\"/"

Alternative Solutions

1. Using Claude skills
2. Adding the common rule to all .ts files
3. Adding the common rule to CLAUDE.md

Priority

Low - Nice to have

Feature Category

Configuration and settings

Use Case Example

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Additional Context

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