chore: pin claude-agent-sdk>=0.1.51 for task_budget support

The to_sdk_config() feature requires task_budget which was added
in claude-agent-sdk 0.1.51.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: flyersworder

README.md

@@ -97,7 +97,7 @@ adapter = DuckDBAdapter("analytics.duckdb")
 tools = create_tools(dc, adapter=adapter)
 ```
 
-### 3. Use with the Claude Agent SDK
+### 3. Use with the Claude Agent SDK (requires `claude-agent-sdk>=0.1.51`)
 
 ```python
 import asyncio

pyproject.toml

@@ -41,7 +41,7 @@ Issues = "https://github.com/flyersworder/agentic-data-contracts/issues"
 Documentation = "https://github.com/flyersworder/agentic-data-contracts/blob/main/docs/architecture.md"
 
 [project.optional-dependencies]
-agent-sdk = ["claude-agent-sdk"]
+agent-sdk = ["claude-agent-sdk>=0.1.51"]
 agent-contracts = ["ai-agent-contracts>=0.2.0"]
 bigquery = ["google-cloud-bigquery"]
 snowflake = ["snowflake-connector-python"]