docs: Simplify and restructure Pods + Serverless + Public Endpoints

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Summary:

Major documentation simplification and restructuring effort. Reduces overall doc size by ~2,100 lines
while improving navigation and discoverability.

Key changes:

• Condense verbose prose into scannable tables, bullet points, and cards
• Restructure troubleshooting to co-locate with relevant products
• Add new "Models" tab for Public Endpoints model reference
• Split large files for better navigation
• Remove redundant "What you'll learn" and "Why use X" sections

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🔧 I noticed that some CI checks failed for this PR. I'm investigating whether the failures are caused by this suggestion. If they're unrelated or pre-existing, I'll leave this suggestion unchanged and create a separate suggestion if a standalone docs fix is needed.