feat: add claudeArgs input for direct CLI argument passing

- Add claude_args input to action.yml for flexible CLI control
- Parse arguments with industry-standard shell-quote library
- Maintain proper argument order: -p [claudeArgs] [legacy] [BASE_ARGS]
- Keep tag mode defaults (needed for functionality)
- Agent mode has no defaults (full user control)
- Add comprehensive tests for new functionality
- Add example workflow showing usage

src/modes/agent/index.ts

@@ -58,28 +58,15 @@ export const agentMode: Mode = {
       promptContent,
     );
 
-    // Export tool environment variables for agent mode
-    const baseTools = [
-      "Edit",
-      "MultiEdit",
-      "Glob",
-      "Grep",
-      "LS",
-      "Read",
-      "Write",
-    ];
-
-    // Add user-specified tools
-    const allowedTools = [...baseTools, ...context.inputs.allowedTools];
-    const disallowedTools = [
-      "WebSearch",
-      "WebFetch",
-      ...context.inputs.disallowedTools,
-    ];
-
-    // Export as INPUT_ prefixed variables for the base action
-    core.exportVariable("INPUT_ALLOWED_TOOLS", allowedTools.join(","));
-    core.exportVariable("INPUT_DISALLOWED_TOOLS", disallowedTools.join(","));
+    // Agent mode: User has full control via claudeArgs or legacy inputs
+    // No default tools are enforced - Claude Code's defaults will apply
+    // Export user-specified tools only if provided
+    if (context.inputs.allowedTools.length > 0) {
+      core.exportVariable("INPUT_ALLOWED_TOOLS", context.inputs.allowedTools.join(","));
+    }
+    if (context.inputs.disallowedTools.length > 0) {
+      core.exportVariable("INPUT_DISALLOWED_TOOLS", context.inputs.disallowedTools.join(","));
+    }
 
     // Agent mode uses a minimal MCP configuration
     // We don't need comment servers or PR-specific tools for automation