Remove retired Amazon templates

[shrey150]

Summary

• remove the TypeScript and Python amazon-global-price-comparison templates
• remove the TypeScript and Python amazon-product-scraping templates
• remove both entries from the repository template index
• remove the retired Amazon slug translation from the playground catalog resolver
• point the resolver's default at the public /api/templates endpoint, so local and CI validation works without injecting TEMPLATES_API_URL

The website catalog already excludes these templates. This completes the cleanup in the public source repository instead of retaining runnable Amazon-specific automation examples on the default branch.

E2E Test Matrix

Command / flow	Observed output	Confidence / sufficiency
pnpm run check:readme-template-index	README template index matches 41 template rows covering 73 first-level template directories.	Proves the authored directory tree and README index remain synchronized after all four directories are removed.
pnpm run format:check && pnpm run lint && pnpm run lint:python && pnpm run format:python:check	All checks passed; 77 Python files already formatted.	Proves the remaining repository passes its standard static checks.
pnpm run ci:playground	With no URL override: built 10 playground TypeScript templates, validated all 10 sources, and ended with Playground CI: build + validation passed.	Proves the canonical public API default works and removing the retired slug translation does not regress any currently exposed playground template.
Query live /api/templates for slugs containing amazon	Zero matching templates.	Confirms the public website/playground catalog remains delisted; this PR removes the remaining source-repository copies.
Repository-wide authored-source search for the two retired slugs/names	Zero matches outside unrelated generic Amazon references.	Confirms README, resolver, and authored template source no longer advertise either retired template.

Production-branch cleanup: #106