fix(demo): analyze conflicts by directory overlap, not fileoverlap

`fileoverlap` was renamed to `pathoverlap` with a `by: file | directory` granularity in #575, and the orchestrator's config loader rejects an unrecognised analyzer type outright — `unknown analyzer type %q` in `normalizeAndValidate` — so the demo profile would have failed at startup rather than quietly falling back to a default.

Picks `by: directory` rather than the `by: file` that matches the old name. The demo spreads each change over a sharded file tree, so keying on the immediate parent directory gives the queue real dependency chains to show while still landing changes in different folders in parallel. Directory overlap is strictly coarser than file overlap: every file overlap is also a directory overlap, and files at the repository root all share one key.

Author: behinddwalls

service/submitqueue/demo/provider/github/profiles.yaml

@@ -17,10 +17,13 @@ queues:
     # Enterprise, add `github: {baseUrl: https://ghe.example.com/api/v3}`.
     changeProvider: {type: github}
 
-    # Serializes only batches that touch a shared file, so independent changes
-    # land in parallel. Swap for {type: all} to serialize the queue entirely, or
-    # {type: none} for maximum parallelism with no conflict detection.
-    analyzer: {type: fileoverlap}
+    # Serializes batches that touch a shared directory, so changes land in
+    # parallel unless they land in the same folder. Keys on the immediate parent
+    # directory, and files at the repository root all share one key. Use
+    # `by: file` to conflict only on the same file, {type: all} to serialize the
+    # queue entirely, or {type: none} for maximum parallelism with no conflict
+    # detection.
+    analyzer: {type: pathoverlap, by: directory}
 
     # Every build succeeds instantly, so a land completes in seconds and the
     # demo exercises the merge rather than waiting on CI.