Add changeset for Phase 2 implementation

Author: elieteyssedou

.changeset/phase-2-raw-element.md

@@ -0,0 +1,11 @@
+---
+'@mcp-pointer/chrome-extension': minor
+---
+
+Send raw DOM element data for server-side processing
+
+- Add extractRawPointedDOMElement() to collect minimal raw DOM data
+- Send outerHTML, boundingClientRect, url, timestamp, computedStyles
+- Include React Fiber when present on element
+- Use DOM_ELEMENT_POINTED message type
+- Move data processing responsibility to server