[High] Cherry-pick critical upstream commits

[randomm]

Problem

Feature branch needs critical fixes from upstream dev.

Commits to Cherry-pick

Must Have (Critical)

1. `b978ca11d` - fix: retry webfetch with simple UA on 403

   • Many web fetches fail without this fix

2. `c4d223eb9` - perf: faster workspace creation

   • Major UX improvement, async workspace creation

Nice to Have

3. `3eaf6f3ba` - fix(ui): show file path in apply_patch request permission screen
4. `3b7c347b2` - tweak: bash tool, ensure cat will trigger external_directory perm

Conflict Risk

• c4d223eb9 (workspace perf) has HIGH conflict risk if feature branch touches worktree/project initialization
• Other commits are LOW risk

Branch

claude/simplify-agentic-loop-2jRSP

[randomm]

All cherry-picks verified complete. All 4 commits (b978ca1, c4d223e, 3eaf6f3, 3b7c347) are present in the feature branch.