Setup Codebase Docs

Build two private docs sites from the code. Move every existing doc into them. Bind future agents to keep them current.

App	Reader	Content
`internal-human-docs`	the owner or founder	How the product works: flows, numbers, money, risks, and decisions, in prose with diagrams
`internal-agent-docs`	coding agents	Exact files, symbols, contracts, invariants, commands, change recipes, runbooks, and reference records

At the end:

Both apps build with Blume 2.x and pass blume validate --strict.
Both apps are private behind a password when deployed.
Old docs folders, runbook folders, and doc-like root notes are gone.
References to old docs paths in the repo now point to the new pages.
Root AGENTS.md sends agents to the agent docs and requires them to update both sites in each change.

setup-codebase-docs