feat: add Chromium extract methods and source mapping (#521)

* feat: add Chromium extract methods, source mapping, and tests

Implement per-category data extraction for Chromium browsers as typed
standalone functions, preparing for Phase 8 wiring into the new
Chromium struct.

New files:
- source.go: dataSource struct, chromiumSources/yandexSources maps,
  yandexQueryOverrides for Yandex action_url variant
- decrypt.go: decryptValue() wrapping platform-specific decryption
- extract_password.go: SQLite + decrypt → []LoginEntry
- extract_cookie.go: SQLite + decrypt → []CookieEntry
- extract_creditcard.go: SQLite + decrypt → []CreditCardEntry
- extract_history.go: SQLite → []HistoryEntry
- extract_download.go: SQLite → []DownloadEntry
- extract_bookmark.go: JSON recursive → []BookmarkEntry
- extract_extension.go: JSON → []ExtensionEntry
- extract_storage.go: LevelDB → []StorageEntry (local + session)
- firefox/source.go: firefoxSources map

Tests use real Chrome table schemas for SQLite fixtures, with INSERT
helpers to keep test data readable and self-documenting.

Ref #520

* fix: remove LevelDB invalid path test (Windows compatibility)

leveldb.OpenFile creates the directory on Windows instead of returning
an error, causing TestExtractLocalStorage_InvalidPath to fail in CI.
This test was verifying LevelDB behavior, not our extraction logic.

* refactor: remove unused query parameter from extract functions

Only extractPasswords needs the query override (Yandex action_url).
The other 7 SQLite extract functions always use their default query,
so remove the unnecessary query parameter from their signatures.

* refactor: use DetectVersion in decryptValue instead of blind fallback

Replace try-then-fallback pattern with explicit version detection using
crypto.DetectVersion. Routes v10 to DecryptWithChromium, DPAPI to
DecryptWithDPAPI, and adds a TODO placeholder for v20 App-Bound
Encryption.

* chore: relax gocognit and gocritic linters for test files

* revert: restore strict gocognit and gocritic linters for test files

* fix: address review feedback on extract methods

- Store DetectVersion result in local variable to avoid duplicate call
- Scan credit card expiration_month/year as int then convert to string
  (matches INTEGER column type in real Chrome schema)
- Add os.Stat check before leveldb.OpenFile to prevent creating empty
  directories for non-existent paths
- Rename TestExtractExtensions_InvalidJSON to
  TestExtractExtensions_MissingSettingsPath (JSON is valid, path is missing)

* fix: revert creditcard scan to string type for NULL safety

modernc.org/sqlite handles INTEGER→string conversion automatically.
Scanning into string is safer for nullable columns — NULL becomes ""
instead of "0" which would be an invalid month/year.

browser/chromium/extract_extension.go

@@ -0,0 +1,59 @@
+package chromium
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/tidwall/gjson"
+
+	"github.com/moond4rk/hackbrowserdata/types"
+)
+
+func extractExtensions(path string) ([]types.ExtensionEntry, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	// Try known JSON paths for extension settings
+	settingKeys := []string{
+		"extensions.settings",
+		"settings.extensions",
+		"settings.settings",
+	}
+	var settings gjson.Result
+	for _, key := range settingKeys {
+		settings = gjson.GetBytes(data, key)
+		if settings.Exists() {
+			break
+		}
+	}
+	if !settings.Exists() {
+		return nil, fmt.Errorf("cannot find extensions in settings")
+	}
+
+	var extensions []types.ExtensionEntry
+	settings.ForEach(func(id, ext gjson.Result) bool {
+		// Skip system/component extensions
+		// https://source.chromium.org/chromium/chromium/src/+/main:extensions/common/mojom/manifest.mojom
+		location := ext.Get("location").Int()
+		if location == 5 || location == 10 {
+			return true
+		}
+
+		manifest := ext.Get("manifest")
+		if !manifest.Exists() {
+			return true
+		}
+
+		extensions = append(extensions, types.ExtensionEntry{
+			Name:        manifest.Get("name").String(),
+			ID:          id.String(),
+			Description: manifest.Get("description").String(),
+			Version:     manifest.Get("version").String(),
+		})
+		return true
+	})
+
+	return extensions, nil
+}