docs: extract cross-app patterns into skill v1.9 and AGENTS.md#1

carlosvin merged 3 commits into

maincarlosvin/tanstack-fullstack-ai-template:mainfrom

docs/skill-v1.9-cross-app-patternscarlosvin/tanstack-fullstack-ai-template:docs/skill-v1.9-cross-app-patternsCopy head branch name to clipboard