v1.39.0.0 feat: buildFetchHandler factory unblocks gbrowser submodule consumption (#1511)

* feat: buildFetchHandler factory unblocks gbrowser submodule consumption

Add buildFetchHandler(cfg: ServerConfig): ServerHandle in browse/src/server.ts.
Refactor start() to delegate handler construction to the factory and read env
once via resolveConfigFromEnv(). Wire the beforeRoute hook (runs after the
tunnel surface filter, before per-route dispatch).

Auth is now cfg-driven end-to-end. Module-level AUTH_TOKEN const +
initRegistry(AUTH_TOKEN) boot call, validateAuth, and shutdown are deleted;
factory closure owns them. start() threads cfg.authToken into launchHeaded,
the state-file write, and the factory.

initRegistry is idempotent for same-token re-init; throws clearly for
different-token re-init. __resetRegistry() test helper added (mirrors
__resetConnectRateLimit). Existing tests that did rotateRoot() ->
initRegistry('fixed-token') swap to __resetRegistry() to avoid the new guard.

14 factory contract tests added covering ServerHandle shape, auth wiring,
validation throws, hook semantics across both surfaces, and registry
idempotency.

Source-pattern tests in dual-listener.test.ts and server-auth.test.ts
updated for the new identifiers (handle.fetchLocal/fetchTunnel, authToken,
shutdownFn).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* chore: bump version and changelog (v1.39.0.0)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.38.1.0",
+  "version": "1.39.0.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",