Support additional agent instruction surfaces

[Pavithran-R-A]

Problem

SetupSentry scans a defined set of instruction files. Some coding agent platforms use instruction surfaces not yet covered.

Proposed Scope

Add support for additional instruction file patterns, such as:

• .windsurfrules (Windsurf)
• .clinerules (Cline)
• .aider* configuration files
• .github/agents/**/*.md
• Other agent-specific instruction files as they emerge

Files/Components

• src/discovery.ts — add new patterns to TARGET_FILES and TARGET_GLOBS
• tests/discovery.test.ts — test new file patterns
• README — update "What Is Scanned" section

Acceptance Criteria

• At least 2 new file patterns added
• Tests for each new pattern
• README "What Is Scanned" updated
• All existing tests still pass