Add --exclude flag to scan command for glob-based file exclusion

[Ibrahimrahhal]

Summary

Adds a new --exclude CLI flag to the scan command that accepts comma-separated glob patterns to exclude files from scanning. This mirrors the existing --target flag but for exclusion.

Usage

# Exclude test files from a full scan
corgea scan --exclude "tests/**,**/*.test.ts"

# Combine with --target for precise control
corgea scan --target "src/" --exclude "**/*.md,**/*.spec.js"

# Multiple patterns
corgea scan --exclude "tests/**,docs/**,**/*.css"

Changes

• src/main.rs: Added --exclude CLI argument to the Scan command (blast-only, matching other blast-specific flags), and passes it through to blast::run.
• src/targets.rs: Added resolve_targets_with_exclude() which filters resolved files against user-provided exclude glob patterns. Added public helpers build_user_exclude_glob_set() and is_file_excluded() for use by the zip creation path. Added 11 unit tests.
• src/scanners/blast.rs: Updated run() signature to accept exclude: Option<String>, passes it to both resolve_targets_with_exclude (for target validation/display) and create_zip_from_target (for zip packaging).
• src/utils/generic.rs: Updated create_zip_from_target() to accept and apply user exclude patterns. For targeted scans, exclusion is handled by resolve_targets_with_exclude. For full repo scans (no --target), exclusion is applied during the directory walk.

Testing

• All 18 unit tests pass (7 existing + 11 new)
• cargo build compiles cleanly with no warnings
• --help output correctly shows the new --exclude flag