chore: drop dead code, sync stale comments

- delete api/categorize.py: orphaned module, never imported. The live
  pzmm-types→category mapping is _types_to_category in mlos_sort.py.
- delete api/adapters.py:_autopick_ambiguous: 5-line wrapper around
  _apply_branch_rules with zero callers in current source.
- delete docs/backlog/polling-path-pz-build.md: described work that
  shipped — init/06_sort_jobs_pz_build.sql plus pz_build plumbing in
  jobs.create_job, app._route_to_job, and app._build_result_for_job.
- sync MAP_LINE convention comment in api/mlos_sort.py with the worker
  copy (Muldraugh, KY is appended at the end, not prepended at the
  front — see adapters.build_response:577).
- update init/04_required_wsids.sql header to reflect the authed-API
  fetch path (HTML scrape was retired in 3a34b71).
- soften the now-stale '~14 rows' count in app._strip_path_prefix's
  docstring.

api/mlos_sort.py

@@ -722,11 +722,11 @@ def sort_mods(
         if wid and wid not in workshop_set:
             workshop_seen.append(wid)
             workshop_set.add(wid)
-    # MAP_LINE convention: dependencies first (leftmost), dependents last
-    # (rightmost). Vanilla Muldraugh, KY is the ultimate base and is
-    # prepended at the very front by adapters.build_response. `order` is
-    # already topo-sorted by mod-level deps so dependencies appear before
-    # their dependents — walk it forward.
+    # MAP_LINE convention: dependencies first (leftmost), dependents next.
+    # Vanilla Muldraugh, KY is ALWAYS appended at the very end by
+    # adapters.build_response. `order` is already topo-sorted by mod-level
+    # deps (require= / loadAfter= / loadBefore=), so dependencies appear
+    # before their dependents — walk it forward.
     map_folders: List[str] = []
     for mod_id in order:
         for mf in by_id[mod_id].maps: