chore(browseros): sync Chromium 148 patches

[Nikhil (shadowfax92)]

Summary

• Updates BrowserOS Chromium patch metadata to Chromium 148.0.7778.97 / base commit 6b3fa66a923a9442c8ab0bc71b4b41ff24528d3b.
• Extracts the remaining ch1 workspace patch state so fresh syncs reproduce BrowserOS assets, generated string resources, server resources, Sparkle payload, and branding/version files.
• Fixes the native BrowserOS Assistant toolbar action so the force-pinned button remains visible by using kEnterpriseControlled instead of kNotPinnable.

Design

This PR keeps the patch repository as the source of truth for the Chromium 148 BrowserOS workspace. The first commit updates patch metadata and extracted patch files for the 148 migration; the follow-up commit completes the extracted workspace state after validating the built app and finding the missing Assistant toolbar icon. The Assistant fix matches Chromium toolbar semantics: kNotPinnable hides a pinned toolbar button, while kEnterpriseControlled keeps the BrowserOS-managed action visible without treating it as a normal optional pin.

Test plan

• browseros-patch status ch1 --verbose
  • needs apply: 0
  • needs update: 0
  • remaining orphaned files are local-only .llm/* and debug.log
• autoninja -C out/Default_arm64 chrome
  • passed after patch sync
  • passed again after the Assistant toolbar fix
• Manual visual check found the missing Assistant icon and drove the toolbar action state fix.

Notes

• The diff is intentionally large because it includes extracted generated assets, branding resources, BrowserOS server resources, and the Sparkle payload required for future fresh-checkout sync reproduction.
• Local generated binary packages/browseros/tools/patch/browseros-patch remains untracked and is not included.
• Customer-journey notes for the CLI workflow were written locally at ~/notes/browseros-patch-usage.md.

[greptile-apps]

Too many files changed for review. (790 files found, 100 file limit)