Release v1.4.20 with comprehensive audit fixes (140 issues) and expanded test coverage

- Speed calculation: raised minimum elapsed floor to 0.5s preventing unrealistic spikes
- Reconnect: exponential backoff with consecutive counter, clock regression protection
- Download engine: retry byte tracking (itemContributedBytes), mkdir before createWriteStream, content-length validation
- Fire-and-forget promises: all void promises now have .catch() error handlers
- Session recovery: normalize stale active statuses to queued on crash recovery, clear speedBps
- Storage: config backup (.bak) before overwrite, EXDEV cross-device rename fallback with type guard
- IPC security: input validation on all string/array IPC handlers, CSP headers in production
- Main process: clipboard memory limit (50KB), installer timing increased to 800ms
- Debrid: attribute-order-independent meta tag regex for Rapidgator filename extraction
- Constants: named constants for magic numbers (MAX_MANIFEST_FILE_BYTES, MAX_LINK_ARTIFACT_BYTES, etc.)
- Extractor/integrity: use shared constants, document password visibility and TOCTOU limitations
- Tests: 103 tests total (55 new), covering utils, storage, integrity, cleanup, extractor, debrid, update

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/update.ts

@@ -69,12 +69,12 @@ function timeoutController(ms: number): { signal: AbortSignal; clear: () => void
   };
 }
 
-function parseVersionParts(version: string): number[] {
+export function parseVersionParts(version: string): number[] {
   const cleaned = version.replace(/^v/i, "").trim();
   return cleaned.split(".").map((part) => Number(part.replace(/[^0-9].*$/, "") || "0"));
 }
 
-function isRemoteNewer(currentVersion: string, latestVersion: string): boolean {
+export function isRemoteNewer(currentVersion: string, latestVersion: string): boolean {
   const current = parseVersionParts(currentVersion);
   const latest = parseVersionParts(latestVersion);
   const maxLen = Math.max(current.length, latest.length);