feat(FN-2944): merge fusion/fn-2944

- test(FN-2944): cover already checked out worktree conflict recovery
- fix(FN-2944): recognize git already checked out worktree conflict
- fix(engine): auto-recover from squash-merge orphan rebase failures

Fusion-Task-Id: FN-2944

packages/pi-claude-cli/src/prompt-builder.ts

@@ -615,7 +615,8 @@ function resolveAgentsMdPath(cwd: string): string | undefined {
   }
 
   // Fall back to global path
-  const globalPath = join(homedir(), ".pi", "agent", "AGENTS.md");
+  const globalHome = process.env.HOME || process.env.USERPROFILE || homedir();
+  const globalPath = join(globalHome, ".pi", "agent", "AGENTS.md");
   if (existsSync(globalPath)) return globalPath;
 
   return undefined;