Refactor addon system: derive module list from build.zig, prune inactive prefixes at runtime

- Eliminate hardcoded module_names in addons.zig — now derived from
  build.zig via all_module_names build option
- Add module_active.zig runtime registry: main.zig registers isActive
  pointers during install(), addons.zig queries them without importing
  each module directly
- Prune embedded file prefixes at startup: after all modules claim
  mutexes, build a runtime active_prefixes table excluding modules we
  don't own. findEmbeddedFile searches only active entries — no
  per-lookup isActive check on the hot path
- Tag both addon and asset prefixes with module_name so pruning applies
  to all embedded files for a module
- Rename src/markers/ → src/worldmarkers/, src/outline/api.zig →
  src/outline/outline.zig to follow {name}/{name}.zig convention

src/outline/model_hook.zig

@@ -14,7 +14,7 @@
 
 const std = @import("std");
 const hook = @import("zhook");
-const api = @import("api.zig");
+const api = @import("outline.zig");
 const o = @import("offsets.zig");
 const types = @import("types.zig");
 const tracker = @import("tracker.zig");