docs(meta): add missing directories to project structure tree

Adds bookmark_portraits, game_rules, and modifier_icons to the
common/ tree. Expands docs/ tree with milestones, events-registry,
IDEAS, REQUIRED_ASSETS, and TESTING entries that were missing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -9,6 +9,7 @@ universe during the Final Empire era. CK3 version 1.18.*.
 lords_of_ash/          # The mod itself (CK3 mod directory)
   common/                       # Game data definitions
     artifacts/                  # Artifact types, slots, visuals (9 Mistborn artifacts)
+    bookmark_portraits/         # Portrait overrides for bookmark characters
     bookmarks/bookmarks/        # Bookmark definitions (CK3 nested convention)
     buildings/                  # Special buildings (Kredik Shaw, Pits, Conventical)
     character_interactions/      # Inquisitor interactions (investigate, interrogate)
@@ -20,9 +21,11 @@ lords_of_ash/          # The mod itself (CK3 mod directory)
     dynasties/                  # 10 Great Houses + Rashek + Terris Stewards
     dynasty_houses/
     education/                  # Custom education focuses (5 Mistborn tracks)
+    game_rules/                 # Narrative/Sandbox mode toggle
     holy_orders/                # Steel Inquisitor order, Keeper Network
     landed_titles/              # Dominances and holdings
     men_at_arms_types/          # Hazekillers, Koloss, Mistborn Agents, Inquisitor Squad
+    modifier_icons/             # Modifier icon path definitions (DDS indirection)
     modifiers/                  # Character and province modifiers
     nicknames/                  # Custom Mistborn nicknames
     on_action/                  # Game hooks (birthday, yearly pulse, game start)
@@ -39,9 +42,14 @@ lords_of_ash/          # The mod itself (CK3 mod directory)
   localization/english/         # All display strings (l_english.yml)
 lords-of-ash.mod       # Outer mod descriptor (has path field)
 docs/
-  lore/                         # Mistborn universe reference material
   bookmarks/                    # Story arc planning (characters, scenarios)
   ck3-modding/                  # CK3 modding reference
+  lore/                         # Mistborn universe reference material
+  milestones/                   # M1–M8 milestone specs and acceptance criteria
+  events-registry.md            # Catalog of ~112 proposed flavor events
+  IDEAS.md                      # Lightweight ideas tracker
+  REQUIRED_ASSETS.md            # Visual asset inventory and specs (~230+ assets)
+  TESTING.md                    # Testing protocol, debug decisions, validation scripts
 ```
 
 ## CK3 Modding Conventions