feat(mcp): implement 4-pillar auto-sync, dynamic introspection, and non-blocking validation

- Pillar 1 (Runtime Auto-Sync):
  * Add sync_agent_tool_schemas() in src/mcp.rs to atomically export live tool schemas & instructions to ~/.gemini/antigravity/mcp/opencadstudio/
  * Automatically invoke sync on MCP startup (mcp::run()) and GUI automation startup (transport::listen())
  * Add --sync-mcp-schemas CLI flag in src/cli.rs and src/main.rs

- Pillar 2 (Development Hook):
  * Strengthen export_agent_tool_schemas test in src/mcp.rs to assert all schema files and instructions.md exist and are in sync on every cargo test run

- Pillar 3 (In-Band Dynamic Introspection):
  * Add 'tools' to READ_OPS in src/mcp.rs and query match in src/app/control/mod.rs
  * Enable agents to dynamically query live tool definitions and instructions via ocs_read (op: 'tools') over MCP or raw socket

- Pillar 4 (Non-Blocking Validation):
  * Set additionalProperties: true on ocs_capture schema in src/mcp.rs to prevent rigid schema rejection of emerging options

src/main.rs

@@ -67,6 +67,16 @@ fn main() -> iced::Result {
             std::process::exit(if ok { 0 } else { 1 });
         }
 
+        if args.sync_mcp_schemas {
+            let synced = mcp::sync_agent_tool_schemas();
+            if synced {
+                println!("Successfully synchronized OpenCADStudio MCP schemas to ~/.gemini/antigravity/mcp/opencadstudio/");
+            } else {
+                eprintln!("Antigravity MCP directory ~/.gemini/antigravity/mcp/ not found; skipped sync.");
+            }
+            return Ok(());
+        }
+
         // MCP is a client-neutral local entry point. It uses only stdin,
         // stdout and the authenticated GUI bridge, so it must run before any
         // logging or graphics setup can write to the protocol stream.