new feature: Relax stat to properly differentiate between directory and file

### Feature Description

Maybe we can relax it a bit for a service that if `abc` is a dir, we return the correct metadata instead of just a `NotFound` error.

### Problem and Solution

For an arbitrary path, `op.stat` expects the user to know whether its a file or directory beforehand so that it can be passed as "a/b/c/" or "a/b/c" or "/a/b/c". the metadata will accordingly contain the mode and if passed incorrectly, stat returns `NotFound` error.

This kind of defeats the purpose of returning `EntryMode` in metadata, and currently there is no deterministic way to directly check if its a file or directory.

### Additional Context

discussed on [discord thread](https://discord.com/channels/1081052318650339399/1434894505836023930).

### Are you willing to contribute to the development of this feature?

- [ ] Yes, I am willing to contribute to the development of this feature.

Start with the op.stat API and EntryMode metadata behavior; no repository files or tests are named, so locate the stat implementation and service-specific behavior first. Compare file and directory paths such as abc, a/b/c, and /a/b/c, then define tests that verify deterministic metadata instead of NotFound when the path type is omitted or mismatched.

Written by the indexing model from the issue text.