feat: support regex matching for package name overrides

[majiayu000]

Fixes #151

Changes

Adds a NameIsRegex boolean field (nameIsRegex in TOML) to PackageOverrideEntry. When set to true, the Name field is treated as a regex pattern instead of an exact string match.

• Uses existing cachedregexp.Compile() for efficient cached compilation
• Anchors the regex with ^...$ to prevent partial matches
• Invalid regex patterns log a warning and do not match (no panic)
• Default behavior (nameIsRegex = false) is unchanged

Example config:

[[PackageOverrides]]
name = "internal-.*"
nameIsRegex = true
ignore = true
reason = "internal packages should not be sent to OSV API"

Test Plan

Added TestConfig_ShouldIgnorePackage_NameIsRegex with 8 test cases:

• Regex match / no match
• Invalid regex handling
• Exact match preserved when nameIsRegex = false
• Empty name with regex flag
• Anchored matching (no partial match)
• Combined with ecosystem filter
• Regex match with ecosystem mismatch

go test ./internal/config/ -run TestConfig_ShouldIgnorePackage_NameIsRegex -v

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[G-Rath]

looks pretty good, though we should update the documentation to reflect the new property and add a CLI test for an invalid regex to showcase the output

[majiayu000]

Thanks for the review! I've addressed the feedback:

1. Moved regex validation to config load time (tryLoadConfig) — invalid regex patterns are now caught once when the config is loaded, instead of warning per package in matches(). This means an invalid regex in a config file will produce a clean config loading error (same behavior as unknown keys).

2. Updated documentation — added nameIsRegex property with an example to docs/configuration.md.

3. Added CLI test — config_file_with_invalid_regex test case verifies the error output when a config has an invalid regex pattern.

[majiayu000]

Hi @G-Rath, I've rebased onto the latest main and addressed the feedback:

1. Regex validation moved to config load time — invalid regex patterns are caught once in tryLoadConfig() instead of per-package warnings
2. Documentation updated — added nameIsRegex property with example to docs/configuration.md
3. CLI test added — config_file_with_invalid_regex test case verifies the error output
4. Fixed errorlint — %v → %w in the regex validation error

Could you please re-review when you get a chance? Thanks!