feat(editor): add standalone world editor (rough/WIP)

Standalone wowee_editor tool for creating custom WoW zones.
This is a rough initial implementation — many features work but
M2/WMO rendering still has issues (frame sync, texture layout
transitions) and needs further polish.

Terrain:
- Create new blank terrain with 10 biome types (Grassland, Forest,
  Jungle, Desert, Barrens, Snow, Swamp, Rocky, Beach, Volcanic)
- Load existing ADT tiles from extracted game data
- Sculpt brushes: Raise, Lower, Smooth, Flatten, Level
- Chunk edge stitching prevents seams between tiles
- Undo/redo (100-deep stack, Ctrl+Z/Ctrl+Shift+Z)
- Save to WoW ADT/WDT format

Texture Painting:
- Paint/Erase/Replace Base modes
- Full tileset texture browser (1285 textures from manifest)
- Per-zone directory filtering and search
- Alpha map editing with 4-layer limit (auto-replaces weakest)

Object Placement:
- M2 and WMO model placement with full manifest browser (11k M2s, 2k WMOs)
- M2Renderer + WMORenderer integrated (loads .skin files for WotLK)
- Ghost preview follows cursor before placing
- Ctrl+click selection, right-click context menu
- Transform gizmo (Move/Rotate/Scale with axis constraints)
- Position/rotation/scale editing in properties panel

NPC/Monster System:
- 631 creature presets scanned from manifest, categorized
  (Critters, Beasts, Humanoids, Undead, Demons, etc.)
- Stats editor: level, health, mana, damage, armor, faction
- Behavior: Stationary, Patrol, Wander, Scripted
- Aggro/leash radius, respawn time, flags (hostile/vendor/etc.)
- Save creature spawns to JSON

Water:
- Place water at configurable height per chunk
- Liquid types: Water, Ocean, Magma, Slime
- Rendered as translucent colored quads
- Saved in ADT MH2O format

Infrastructure:
- Free-fly camera (WASD/QE, right-drag look, scroll speed)
- 5-mode toolbar: Sculpt | Paint | Objects | Water | NPCs
- Asset browser indexes full manifest on startup
- Editor water/marker shaders (pos+color vertex format)
- forceNoCull added to M2Renderer for editor use
- AssetManifest::getEntries() and AssetManager::getManifest() exposed

Known issues:
- M2/WMO rendering may not display on first placement (frame index
  sync between update/render was misaligned — now fixed but untested
  end-to-end)
- Validation layer errors on shutdown (resource cleanup ordering)
- Object placement on steep terrain can miss raycast
- No undo for texture painting or object placement yet

tools/editor/asset_browser.cpp

@@ -0,0 +1,98 @@
+#include "asset_browser.hpp"
+#include "pipeline/asset_manager.hpp"
+#include "pipeline/asset_manifest.hpp"
+#include "core/logger.hpp"
+#include <algorithm>
+#include <set>
+
+namespace wowee {
+namespace editor {
+
+std::string AssetBrowser::extractFilename(const std::string& path) {
+    auto pos = path.rfind('\\');
+    return pos != std::string::npos ? path.substr(pos + 1) : path;
+}
+
+std::string AssetBrowser::extractDirectory(const std::string& path) {
+    auto pos = path.rfind('\\');
+    return pos != std::string::npos ? path.substr(0, pos) : "";
+}
+
+void AssetBrowser::initialize(pipeline::AssetManager* am) {
+    if (initialized_ || !am) return;
+    initialized_ = true;
+
+    const auto& entries = am->getManifest().getEntries();
+
+    std::set<std::string> texDirSet, m2DirSet, wmoDirSet;
+
+    for (const auto& [path, entry] : entries) {
+        // Tileset textures
+        if (path.starts_with("tileset\\") && path.ends_with(".blp")) {
+            // Skip specular/normal maps
+            if (path.ends_with("_s.blp") || path.ends_with("_h.blp") ||
+                path.ends_with("_n.blp")) continue;
+
+            AssetEntry ae;
+            ae.wowPath = path;
+            ae.displayName = extractFilename(path);
+            ae.directory = extractDirectory(path);
+            textures_.push_back(ae);
+            texDirSet.insert(ae.directory);
+        }
+
+        // M2 models (world doodads)
+        if (path.ends_with(".m2")) {
+            // Focus on world assets, skip character/creature/item models
+            if (path.starts_with("world\\") || path.starts_with("dungeons\\")) {
+                AssetEntry ae;
+                ae.wowPath = path;
+                ae.displayName = extractFilename(path);
+                ae.directory = extractDirectory(path);
+                m2Models_.push_back(ae);
+                m2DirSet.insert(ae.directory);
+            }
+        }
+
+        // WMOs
+        if (path.ends_with(".wmo") && !path.ends_with("_lod.wmo")) {
+            // Skip group files (_000.wmo, _001.wmo, etc.)
+            bool isGroup = false;
+            if (path.size() > 8) {
+                auto base = path.substr(path.size() - 8);
+                if (base[0] == '_' && std::isdigit(base[1]) && std::isdigit(base[2]) &&
+                    std::isdigit(base[3]))
+                    isGroup = true;
+            }
+            if (isGroup) continue;
+
+            AssetEntry ae;
+            ae.wowPath = path;
+            ae.displayName = extractFilename(path);
+            ae.directory = extractDirectory(path);
+            wmos_.push_back(ae);
+            wmoDirSet.insert(ae.directory);
+        }
+    }
+
+    std::sort(textures_.begin(), textures_.end(),
+              [](const AssetEntry& a, const AssetEntry& b) { return a.wowPath < b.wowPath; });
+    std::sort(m2Models_.begin(), m2Models_.end(),
+              [](const AssetEntry& a, const AssetEntry& b) { return a.wowPath < b.wowPath; });
+    std::sort(wmos_.begin(), wmos_.end(),
+              [](const AssetEntry& a, const AssetEntry& b) { return a.wowPath < b.wowPath; });
+
+    textureDirs_.assign(texDirSet.begin(), texDirSet.end());
+    m2Dirs_.assign(m2DirSet.begin(), m2DirSet.end());
+    wmoDirs_.assign(wmoDirSet.begin(), wmoDirSet.end());
+
+    std::sort(textureDirs_.begin(), textureDirs_.end());
+    std::sort(m2Dirs_.begin(), m2Dirs_.end());
+    std::sort(wmoDirs_.begin(), wmoDirs_.end());
+
+    LOG_INFO("Asset browser: ", textures_.size(), " textures, ",
+             m2Models_.size(), " M2s, ", wmos_.size(), " WMOs indexed");
+}
+
+} // namespace editor
+} // namespace wowee