feat(tools): add per-tool result size thresholds and search_files output cap

Declares max_result_size_chars on each tool registration so the persistence
layer can apply per-tool limits instead of the global 50K default. Adds a
Layer 1 output cap inside search_tool() to prevent context overflow, and
adds a schema maximum of 10000 to the search_files limit parameter.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tools/code_execution_tool.py

@@ -1344,4 +1344,5 @@ registry.register(
         enabled_tools=kw.get("enabled_tools")),
     check_fn=check_sandbox_requirements,
     emoji="🐍",
+    max_result_size_chars=30_000,
 )