Add llms-full.txt with complete documentation content

Contains the full text of all current documentation pages (v2.0.2)
stripped of frontmatter, for LLMs that prefer ingesting complete
content at once. Companion to llms.txt which provides the index.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: schwzr