feat(ptc): fix WASM wiring, add ptc_script tool, nesting depth, Docker SDK

- Fix WASM tool_invoke production wiring: change tool_executor to a
  shared Arc<std::sync::RwLock> slot with lazy resolution so WASM tools
  registered during build_all() can access the executor set afterward
- Add nesting_depth field to ToolCallRequest and propagate it through
  the orchestrator's tool_call_handler into JobContext
- Add ptc_script built-in tool: runs Python scripts with ironclaw_tools
  SDK pre-imported, env-scrubbed subprocess, structured output support
- Copy Python SDK into Docker worker image at dist-packages path

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Dockerfile.worker

@@ -55,6 +55,9 @@ RUN npm install -g @anthropic-ai/claude-code@latest
 # Copy the binary
 COPY --from=builder /build/target/release/ironclaw /usr/local/bin/ironclaw
 
+# Install IronClaw Python SDK for programmatic tool calling (PTC)
+COPY sdk/python/ironclaw_tools.py /usr/lib/python3/dist-packages/ironclaw_tools.py
+
 # Create non-root user (UID 1000 matches the orchestrator's container config)
 RUN useradd -m -u 1000 -s /bin/bash sandbox \
     && mkdir -p /workspace \