feat: add structured output support

Add support for Agent SDK structured outputs.

New input: json_schema - JSON schema for validated outputs
Auto-sets GitHub Action outputs for each field

Security:
- Reserved output protection (prevents shadowing)
- 1MB output size limits enforced
- Output key format validation
- Objects/arrays >1MB skipped (not truncated to invalid JSON)

Tests:
- 26 unit tests
- 5 integration tests
- 480 tests passing

Docs: https://docs.claude.com/en/docs/agent-sdk/structured-outputs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

base-action/action.yml

@@ -24,6 +24,10 @@ inputs:
     description: "Additional arguments to pass directly to Claude CLI (e.g., '--max-turns 3 --mcp-config /path/to/config.json')"
     required: false
     default: ""
+  allowed_tools:
+    description: "Comma-separated list of allowed tools (e.g., 'Read,Write,Bash'). Passed as --allowedTools to Claude CLI"
+    required: false
+    default: ""
 
   # Authentication settings
   anthropic_api_key:
@@ -67,6 +71,20 @@ inputs:
     description: "Newline-separated list of Claude Code plugin marketplace Git URLs to install from (e.g., 'https://github.com/user/marketplace1.git\nhttps://github.com/user/marketplace2.git')"
     required: false
     default: ""
+  json_schema:
+    description: |
+      JSON schema for structured output validation.  Claude must return JSON matching this schema 
+      or the action will fail. Outputs are automatically set for each field.
+
+      Access outputs via: steps.<step-id>.outputs.<field_name>
+
+      Limitations:
+      - Field names must start with letter or underscore (A-Z, a-z, _)
+      - Special characters in field names are replaced with underscores
+      - Each output is limited to 1MB (values will be truncated)
+      - Objects and arrays are JSON stringified
+    required: false
+    default: ""
 
 outputs:
   conclusion:
@@ -111,7 +129,7 @@ runs:
       run: |
         if [ -z "${{ inputs.path_to_claude_code_executable }}" ]; then
           echo "Installing Claude Code..."
-          curl -fsSL https://claude.ai/install.sh | bash -s 2.0.42
+          curl -fsSL https://claude.ai/install.sh | bash -s 2.0.45
         else
           echo "Using custom Claude Code executable: ${{ inputs.path_to_claude_code_executable }}"
           # Add the directory containing the custom executable to PATH
@@ -141,6 +159,8 @@ runs:
         INPUT_SHOW_FULL_OUTPUT: ${{ inputs.show_full_output }}
         INPUT_PLUGINS: ${{ inputs.plugins }}
         INPUT_PLUGIN_MARKETPLACES: ${{ inputs.plugin_marketplaces }}
+        INPUT_ALLOWED_TOOLS: ${{ inputs.allowed_tools }}
+        JSON_SCHEMA: ${{ inputs.json_schema }}
 
         # Provider configuration
         ANTHROPIC_API_KEY: ${{ inputs.anthropic_api_key }}