Add /llms-full.txt and script to generate it (#1300)

* Add script to generate content_catalog.json (similar to llms-full.txt)

As a cleanup, this PR also removes the old apply_image_effects.py and
the accompanying blurmask.png.

* Add script to generate llms-full.txt

* Add "make llms" command and make "make export" depend on it.

Author: sfc-gh-tteixeira

makefile

@@ -11,9 +11,13 @@ start:
 	npm run start
 
 .PHONY: export
-export:
+export: llms
 	npm run export
 
+.PHONY: llms
+llms:
+	uv run python/generate_llms_full_txt.py
+
 .PHONY: lint
 lint:
 	npm run lint