Add contextID in state

Signed-off-by: Francis Bouvier <francis@lightpanda.io>

src/cdp/cdp.zig

@@ -88,6 +88,7 @@ pub fn do(
 }
 
 pub const State = struct {
+    contextID: ?[]const u8 = null,
     frameID: []const u8 = FrameID,
     url: []const u8 = URLBase,
     securityOrigin: []const u8 = URLBase,

src/cdp/target.zig

@@ -178,6 +178,8 @@ fn createBrowserContext(
     };
     const msg = try getMsg(alloc, Params, scanner);
 
+    ctx.state.contextID = ContextID;
+
     // output
     const Resp = struct {
         browserContextId: []const u8 = ContextID,