v1.91.4.0 fix: Windows Opera cookie import wave (#2980, refs #2957) (#2987)

* fix: support Windows Opera and Opera GX cookie imports

Fixes #2957

* fix: repair Windows cookie decryption and make Opera import failures actionable

- strip the SHA-256(host_key) prefix Chromium adds to v10 values (DB meta v24+) on Windows
- keep receipts and name `$B handoff` recovery for App-Bound rows in browsers without native extraction
- explain missing browsers, missing profiles and ambiguous profile selection with next steps
- add windowsNative/resolveBrowserInfo, the operagx alias and sorted failure reasons in CLI output
- cover the Node server runtime with a real-DPAPI Windows test

* docs: document Windows Opera cookie import and guard browser lists against drift

* chore: file cookie-import follow-ups from the Opera fix wave review

* test: keep Opera receipt tests independent of the shared key cache

* test: declare generated gstack/llms.txt as a command-reference input for PR selection

* chore: release v1.91.4.0

* test: reconstruct the historical cookie-workflow approval after the Opera BROWSER.md additions

* test: run the real-DPAPI Windows check with the runner's environment

PowerShell launched with a stripped environment took ~18-21s on the Windows
runner (measured on a throwaway diagnostics run), past dpapiDecrypt's 10s
deadline; with the full environment it returns in ~0.3s. Only APPDATA is
redirected to the fixture's Opera root.

---------

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>

gstack/llms.txt

@@ -97,7 +97,7 @@ Run with `browse <command> [args]`. Full reference: `browse/SKILL.md`.
 - `click <sel>`: Click element
 - `cookie <name>=<value>`: Set cookie on current page domain
 - `cookie-import <json>`: Import cookies from JSON file
-- `cookie-import-browser [browser] [--domain d] [--profile p] [--all] [--clear-storage] [--verify-auth]`: Copy cookies from chrome, chromium, brave, edge, or macOS-only comet, arc, dia.
+- `cookie-import-browser [browser] [--domain d] [--profile p] [--all] [--clear-storage] [--verify-auth]`: Copy cookies from chrome, chromium, brave, edge, Windows-only opera, opera-gx, or macOS-only comet, arc, dia.
 - `dialog-accept [text]`: Auto-accept next alert/confirm/prompt.
 - `dialog-dismiss`: Auto-dismiss next dialog
 - `fill <sel> <val>`: Fill input