Seed an AI-legible project memory map that stays small

One file (AGENTS.md) that bootstraps the rest: rules, the file map to create,
what belongs in each file, the first-session interview order, and the list of
anti-patterns that killed the previous map (1,308-line guide, 63 task files,
narrative history inline, sessions skimming 56k tokens of context).

Separates four kinds of content by read frequency:
  rules/invariants  -> AGENTS.md          (every session)
  subsystem truth   -> docs/ai/<topic>.md (only the matching one)
  lookups           -> environment.md     (grepped, never read)
  retired decisions -> decisions.md       (only when re-opening one)

Caps are enforced, not promised: scripts/verify.sh checks doc budgets before
the build, so a commit that pads a capped file fails. Proven both ways — it
passes clean and exits 1 on an over-cap file.

scripts/scope-check.sh blocks edits outside the declared file list.
templates/ holds fill-in skeletons for the seven files a project must create.

CC0: copy it, rename it, sell it, no attribution needed.

templates/index.md

@@ -0,0 +1,9 @@
+# <dir> — index
+
+One line on what this directory owns, then every file with its purpose. Details live in the files.
+
+| File | Purpose |
+|---|---|
+| `<File>` | <what it does, one line> |
+
+Related: [`../other/index.md`](../other/index.md)