fix(docs): standardize C4A-Script tutorial, add CLI identity-based crawling, and add sponsorship CTA

- Switch installs to pip install -r requirements.txt (tutorial and app docs)
- Update local run steps to python server.py and http://localhost:8000
- Set default PORT to 8000; update port-in-use commands and alt port 8001
- Replace unsupported :contains() example with accessible attribute selector
- Update example URLs in tutorial servers to 127.0.0.1:8000
- Add “Identity-based crawling” section with crwl profiles CLI workflow and code usage
- Replace legacy-docs note with sponsorship message in docs/md_v2/index.md
- Minor copy and consistency fixes across pages

docs/md_v2/core/c4a-script.md

@@ -69,12 +69,12 @@ The tutorial includes a Flask-based web interface with:
 cd docs/examples/c4a_script/tutorial/
 
 # Install dependencies
-pip install flask
+pip install -r requirements.txt
 
 # Launch the tutorial server
-python app.py
+python server.py
 
-# Open http://localhost:5000 in your browser
+# Open http://localhost:8000 in your browser
 ```
 
 ## Core Concepts
@@ -111,8 +111,8 @@ CLICK `.submit-btn`
 # By attribute
 CLICK `button[type="submit"]`
 
-# By text content
-CLICK `button:contains("Sign In")`
+# By accessible attributes
+CLICK `button[aria-label="Search"][title="Search"]`
 
 # Complex selectors
 CLICK `.form-container input[name="email"]`