chore: remove dead expand() function and skills/ bootstrap dirs

expand() had zero callers anywhere in the codebase. The skills/bash,
skills/powershell, and skills/python directories were created on every
startup but the skills/ tree is not part of the current architecture.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pyra/config/dirs.py

@@ -33,9 +33,6 @@ def bootstrap() -> None:
     ensure_dir(home / "memory" / "user", 0o700)
     ensure_dir(home / "memory" / "context", 0o700)
     ensure_dir(home / "memory" / "knowledge", 0o700)
-    ensure_dir(home / "skills" / "bash", 0o700)
-    ensure_dir(home / "skills" / "powershell", 0o700)
-    ensure_dir(home / "skills" / "python", 0o700)
     ensure_dir(home / "vault" / "secrets", 0o700)
     ensure_dir(home / "plugins", 0o700)
     ensure_dir(home / "logs", 0o700)

src/pyra/utils/paths.py

@@ -17,5 +17,3 @@ def safe_chmod(path: Path, mode: int) -> None:
         path.chmod(mode)
 
 
-def expand(p: str) -> Path:
-    return Path(p).expanduser().resolve()