feat: add load_textures + extend load_rig with asset_aliases

puppet.load_textures(rig, asset_aliases):
- Resolves bone.texture atlas-ids to texture-handles via the asset-
  lib indirection. Reads asset_aliases[rig.asset_pack] to get the
  asset-lib id, loads the lib's atlas.json, looks up the atlas-entry
  by id, then calls engine.asset.load_texture on the resolved file
  path.
- Resolves bone.anchor from the atlas entry unless the bone has an
  explicit anchor override.
- Raises clear errors when alias/atlas-pack/atlas-id is missing.

puppet.load_rig(path, asset_aliases?) now optionally calls
load_textures after build_rig if asset_aliases is supplied.

README updated with new API entries (load_rig signature, load_textures,
bone_world_transform, write_bone_test_only) and CHANGELOG v0.2.0 entry.

README.md

@@ -5,7 +5,7 @@ tracks, rest pose, keyframe animations, procedural animations
 (Lua-side), and look-at constraint. No footplant IK in v0.1
 (deferred).
 
-**Version:** 0.1.0
+**Version:** 0.2.0
 **Lib-ID:** lib-core.puppet
 **Requires:** (none — pure Lua + engine.render.*)
 **Tags:** animation, skeleton, puppet, character
@@ -72,10 +72,37 @@ Keyframe-layer controls. Animation must be registered via
 Binds a built animation (from `build_animation`) to a puppet
 instance, making it available to `play`.
 
-### `puppet.load_rig(path)`, `puppet.load_animation(path)`
+### `puppet.load_rig(path, asset_aliases?)`
 
-Convenience wrappers: read JSON file via `engine.asset.read_file` +
+Loads a rig from a JSON file and optionally resolves its bone textures
-parse + call `build_rig` / `build_animation`.
+via `puppet.load_textures`. Pass the module's `asset_aliases` table
+(from `engine.module.asset_aliases()`) to enable sprite-mode rendering;
+omit for colored-rect-only rigs.
+
+### `puppet.load_textures(rig, asset_aliases)`
+
+For each bone with a `texture` field, resolves the atlas-id to a
+texture-handle via the asset-lib indirection: read `asset_aliases[rig.asset_pack]`
+to get the lib-id, load `<lib-id>/assets/atlas.json`, look up the
+atlas-entry by id, and call `engine.asset.load_texture` on the file
+path. Also resolves bone anchors from the atlas (unless bone has an
+explicit `anchor` field).
+
+### `puppet.bone_world_transform(handle, bone_id)`
+
+Returns the bone's cached world-transform `(x, y, angle)` from the
+last `puppet.update` tick. Used by tests and by modules needing world-
+space queries (e.g., for spawning effects at a bone position).
+
+### `puppet.write_bone_test_only(handle, bone_id, angle_rad)`
+
+Test-setup helper: directly write a bone angle bypassing the track-
+conflict-guard. Not for production use; modules should write via
+procedural callbacks.
+
+### `puppet.load_animation(path, rig)`
+
+Convenience wrapper: reads a JSON file and calls `build_animation`.
 
 ### `puppet.position(p)`, `puppet.facing(p)`, `puppet.move_to(p, x, y)`
 
@@ -98,6 +125,15 @@ ownership at write time.
 
 ## CHANGELOG
 
+### v0.2.0
+- Rig-format extension (texture, z_order, scale, anchor, asset_pack
+  fields on bones; rig.bones_z_sorted for render-order)
+- Multi-level parent-chain transform with depth-first update pipeline
+- Sprite-mode render via engine.render.draw_sprite_transform
+- New API: load_textures, bone_world_transform, write_bone_test_only
+- All v0.1.0 rigs continue to work (texture-less bones fall back to
+  colored-rect render)
+
 ### v0.1.0
 - Initial release: skeleton + bones + tracks + rest + keyframe +
   procedural + look-at constraint. Footplant IK deferred.

init.lua

@@ -576,9 +576,55 @@ end
 -- ====================================================================
 -- engine.asset.load_json(path) reads the file and parses JSON in one
 -- call, returning a Lua table directly. No separate decode step needed.
-function M.load_rig(path)
+
+-- ====================================================================
+-- Resolve atlas-ids to texture-handles via asset-lib indirection.
+-- asset_aliases: { [alias-key] = asset-lib-id } from module's manifest.
+-- ====================================================================
+function M.load_textures(rig, asset_aliases)
+    if rig.asset_pack == nil then return end  -- no-texture rig, nothing to do
+    local lib_id = asset_aliases[rig.asset_pack]
+    if lib_id == nil then
+        error("puppet.load_textures: asset-pack alias '" .. rig.asset_pack
+              .. "' not found in module asset_aliases")
+    end
+    local atlas_path = lib_id .. "/assets/atlas.json"
+    local atlas = engine.asset.load_json(atlas_path)
+    local pack = atlas[rig.asset_pack]
+    if pack == nil then
+        error("puppet.load_textures: asset_pack '" .. rig.asset_pack
+              .. "' not declared in atlas of '" .. lib_id .. "'")
+    end
+    for _, b in pairs(rig.bones_by_id) do
+        if b.texture then
+            local entry = pack[b.texture]
+            if entry == nil then
+                error("puppet.load_textures: atlas-id '" .. b.texture
+                      .. "' not in asset_pack '" .. rig.asset_pack
+                      .. "' of '" .. lib_id .. "'")
+            end
+            local tex_path = lib_id .. "/assets/" .. entry.file
+            b.texture_handle = engine.asset.load_texture(tex_path)
+            -- Resolve anchor: bone.anchor override beats atlas-default.
+            if b.anchor == nil then
+                b.anchor = entry.anchor or { 0, 0 }
+            end
+        end
+    end
+end
+
+-- ====================================================================
+-- Load a rig from a JSON file and optionally resolve textures.
+-- asset_aliases is the module-level alias map (from manifest.module);
+-- pass engine.module.asset_aliases() in module init.lua.
+-- ====================================================================
+function M.load_rig(path, asset_aliases)
     local rig_table = engine.asset.load_json(path)
-    return M.build_rig(rig_table)
+    local rig = M.build_rig(rig_table)
+    if asset_aliases then
+        M.load_textures(rig, asset_aliases)
+    end
+    return rig
 end
 
 function M.load_animation(path, rig)