docs(test): add fileoverview headers to comprehensive test files

Add descriptive @fileoverview headers to comprehensive test suites:
- purl-edge-cases.test.mts: edge cases, coverage, boundary conditions
- purl-spec.test.mts: official purl-spec compliance validation

Author: jdalton

test/purl-edge-cases.test.mts

@@ -20,6 +20,13 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
+/**
+ * @fileoverview Comprehensive edge case and coverage tests for PackageURL.
+ * Tests URL scheme handling, component validation, special characters, version separators,
+ * subpath/qualifier handling, type-specific normalizations, parameter types, roundtrip
+ * consistency, error messages, encoding/decoding, normalization, validation, and internal utilities.
+ * This file aims for complete code coverage of all edge cases and boundary conditions.
+ */
 import { describe, expect, it } from 'vitest'
 
 import {

test/purl-spec.test.mts

@@ -20,6 +20,12 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
+/**
+ * @fileoverview Official Package URL specification compliance tests.
+ * Tests PackageURL implementation against the official purl-spec test suite (test/data/*.json).
+ * Validates parsing, building, and roundtrip behavior for all package types defined in the spec,
+ * ensuring strict compliance with expected successes and failures.
+ */
 import path from 'node:path'
 
 import { glob } from 'fast-glob'