Add EU7 PACK v11 UTEX, section unload, and LRU streaming caches

Bake deduplicated section texture lists (UTEX) and read them at runtime so
texture warm/prefetch no longer scans every instance. Evict PACK sections
outside a 16 km keep ring and cap mesh/nodedata/texture warm caches to stop
RAM and apply cost from growing without bound during long fast camera flight.

- Bake v11 (format=4): UMES + UTEX + CHNK; mesh/texture ordering by frequency
- Runtime: incremental UTEX warm, adaptive apply slices, preempt/catchup tuning
- Unload: track instances per section, Region erase, pack pool release
- LRU: mesh/nodedata (2000, ref-counted), warmed textures (2048)
- Bench/diagnostics: unload and cache eviction counters
- Fix pack instance erase in Region; resolve duplicate helper symbols

docs/eu7-format.md

@@ -853,6 +853,30 @@ Powtórzone chunk_count razy:
 Runtime: worker czyta `read_pack_section_chunk_load(row, col, chunk_index)` z O(1) seek.
 Sekcje v9 (format=2) i v7 flat pozostają kompatybilne (`chunk_count` implicit = 1).
 
+### Format sekcji — v11 UTEX (`kPackSectionFormatV11 = 4`)
+
+Rozszerzenie v10: po UMES deduplikowana lista ścieżek tekstur (`texture_file`), posortowana po częstotliwości.
+
+```
+uint8    section_format    — musi być = 4
+uint32   solo_count
+uint32   inst_count
+uint32   unique_mesh_count
+uint32[unique_mesh_count] string_id
+
+uint32   unique_texture_count
+uint32[unique_texture_count] string_id   — texture_file (pomija none/make:/@/#/.e3d)
+
+uint32   chunk_count
+Powtórzone chunk_count razy:
+    uint32   chunk_model_count
+    uint32   chunk_byte_offset
+
+[payload chunków]
+```
+
+Runtime używa UTEX do prefetch/warm tekstur bez skanowania wszystkich instancji.
+
 ---
 
 ## 30. PROT — prototypy modeli (v8+)