feat(skills): add blender-mcp optional skill for 3D modeling

Control a running Blender instance from Hermes via socket connection
to the blender-mcp addon (port 9876). Supports creating 3D objects,
materials, animations, and running arbitrary bpy code.

Placed in optional-skills/ since it requires Blender 4.3+ desktop
with a third-party addon manually started each session.

optional-skills/creative/blender-mcp/SKILL.md

@@ -0,0 +1,116 @@
+---
+name: blender-mcp
+description: Control Blender directly from Hermes via socket connection to the blender-mcp addon. Create 3D objects, materials, animations, and run arbitrary Blender Python (bpy) code. Use when user wants to create or modify anything in Blender.
+version: 1.0.0
+requires: Blender 4.3+ (desktop instance required, headless not supported)
+author: alireza78a
+tags: [blender, 3d, animation, modeling, bpy, mcp]
+---
+
+# Blender MCP
+
+Control a running Blender instance from Hermes via socket on TCP port 9876.
+
+## Setup (one-time)
+
+### 1. Install the Blender addon
+
+    curl -sL https://raw.githubusercontent.com/ahujasid/blender-mcp/main/addon.py -o ~/Desktop/blender_mcp_addon.py
+
+In Blender:
+    Edit > Preferences > Add-ons > Install > select blender_mcp_addon.py
+    Enable "Interface: Blender MCP"
+
+### 2. Start the socket server in Blender
+
+Press N in Blender viewport to open sidebar.
+Find "BlenderMCP" tab and click "Start Server".
+
+### 3. Verify connection
+
+    nc -z -w2 localhost 9876 && echo "OPEN" || echo "CLOSED"
+
+## Protocol
+
+Plain UTF-8 JSON over TCP -- no length prefix.
+
+Send:     {"type": "<command>", "params": {<kwargs>}}
+Receive:  {"status": "success", "result": <value>}
+          {"status": "error",   "message": "<reason>"}
+
+## Available Commands
+
+| type                    | params            | description                     |
+|-------------------------|-------------------|---------------------------------|
+| execute_code            | code (str)        | Run arbitrary bpy Python code   |
+| get_scene_info          | (none)            | List all objects in scene       |
+| get_object_info         | object_name (str) | Details on a specific object    |
+| get_viewport_screenshot | (none)            | Screenshot of current viewport  |
+
+## Python Helper
+
+Use this inside execute_code tool calls:
+
+    import socket, json
+
+    def blender_exec(code: str, host="localhost", port=9876, timeout=15):
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.connect((host, port))
+        s.settimeout(timeout)
+        payload = json.dumps({"type": "execute_code", "params": {"code": code}})
+        s.sendall(payload.encode("utf-8"))
+        buf = b""
+        while True:
+            try:
+                chunk = s.recv(4096)
+                if not chunk:
+                    break
+                buf += chunk
+                try:
+                    json.loads(buf.decode("utf-8"))
+                    break
+                except json.JSONDecodeError:
+                    continue
+            except socket.timeout:
+                break
+        s.close()
+        return json.loads(buf.decode("utf-8"))
+
+## Common bpy Patterns
+
+### Clear scene
+    bpy.ops.object.select_all(action='SELECT')
+    bpy.ops.object.delete()
+
+### Add mesh objects
+    bpy.ops.mesh.primitive_uv_sphere_add(radius=1, location=(0, 0, 0))
+    bpy.ops.mesh.primitive_cube_add(size=2, location=(3, 0, 0))
+    bpy.ops.mesh.primitive_cylinder_add(radius=0.5, depth=2, location=(-3, 0, 0))
+
+### Create and assign material
+    mat = bpy.data.materials.new(name="MyMat")
+    mat.use_nodes = True
+    bsdf = mat.node_tree.nodes.get("Principled BSDF")
+    bsdf.inputs["Base Color"].default_value = (R, G, B, 1.0)
+    bsdf.inputs["Roughness"].default_value = 0.3
+    bsdf.inputs["Metallic"].default_value = 0.0
+    obj.data.materials.append(mat)
+
+### Keyframe animation
+    obj.location = (0, 0, 0)
+    obj.keyframe_insert(data_path="location", frame=1)
+    obj.location = (0, 0, 3)
+    obj.keyframe_insert(data_path="location", frame=60)
+
+### Render to file
+    bpy.context.scene.render.filepath = "/tmp/render.png"
+    bpy.context.scene.render.engine = 'CYCLES'
+    bpy.ops.render.render(write_still=True)
+
+## Pitfalls
+
+- Must check socket is open before running (nc -z localhost 9876)
+- Addon server must be started inside Blender each session (N-panel > BlenderMCP > Connect)
+- Break complex scenes into multiple smaller execute_code calls to avoid timeouts
+- Render output path must be absolute (/tmp/...) not relative
+- shade_smooth() requires object to be selected and in object mode