refactor: clean up legacy code, rename hopper to entity_extractor, and add third-party notices

- Add NOTICE file and README license references for mobile-use and finalrun-agent
- Add derivative attribution headers to 17 files derived from mobile-use
- Rename hopper agent to entity_extractor across prompts, tools, and configs
- Remove obsolete adb_tunnel, ApiBaseUrl, and legacy CLI utility scripts
- Replace legacy examples with native Artemis diagnostic and workflow examples
- Update unit and tool tests to validate entity_extractor and SDK builders

.env.example

@@ -9,7 +9,7 @@ GEMINI_API_KEY=
 GOOGLE_API_KEY=
 OPENAI_API_KEY=
 ANTHROPIC_API_KEY=
-OPEN_ROUTER_API_KEY=
+OPENROUTER_API_KEY=
 XAI_API_KEY=
 
 # Google Cloud Vision OCR (Optional - for advanced OCR processing)