refactor: split auto-rules into modpack/ vs curated/ provenance subdirs

The previous flat data/rules/ flattened a real distinction:
  - data/rules/modpack/  mirrors of upstream modpack-author-bundled
                         sorting_rules.txt (HellDrinx). Update when
                         upstream publishes; don't unilaterally edit.
  - data/rules/curated/  sortof-operator-authored rules for individual
                         mods whose authors didn't declare load order
                         in their mod.info (RV Interior Expansion).

The loader stays provenance-agnostic; trigger values in _RULES_TRIGGERS
are paths relative to data/rules/ ("modpack/helldrinx.txt" etc.).
File headers in each rules file declare the provenance category and
edit policy.

data/rules/curated/rv_expansion.txt

@@ -0,0 +1,22 @@
+; RV Interior Expansion (B42) — sortof-operator-curated sorting rules.
+; Provenance: data/rules/curated/. Edit freely when authoring new
+; load-order constraints for mods whose authors didn't declare them.
+;
+; Triggers:
+;   - 3618427553 (RVInteriorExpansion, map folder rvupdate)
+;   - 3622163276 (RVInteriorExpansionPart2, map folder rv2)
+; Auto-injected by app.py:_auto_rules_for() when either trigger wsid is
+; in the user's input. User-supplied rules are appended afterward and
+; override these on conflicting keys.
+;
+; Authored ordering: PROJECTRVInterior42 → RVInteriorExpansion → RVInteriorExpansionPart2.
+; The expansion mods don't declare these loadAfter relationships in their own
+; mod.info, so without these rules sortof has nothing to base the cluster
+; ordering on (PROJECTRVInterior42 is in PREORDER slot 7 already; expansions
+; just need to chain off of it).
+
+[RVInteriorExpansion]
+loadAfter=PROJECTRVInterior42
+
+[RVInteriorExpansionPart2]
+loadAfter=RVInteriorExpansion