docs: bring every document in line with the current build

README rewritten around the actual state (walkable DemoMap, blockout facades,
planned patches); Tools/README now lists all seventeen tools by role; build.md
gains the content pipeline table and the two enforced rules (one unit conversion,
collision decided at import). Setup gains a content-pipeline row, the toolchain
state notes the demo level exercises the engine path, release checks record the
Blender pre-check that backs traversal, PLAN points at ROADMAP/MEMORY/Screenshots,
and THIRD_PARTY_NOTICES gains rows for the hero facade and the candidate props.

Also fixed the last stale reference to Geo/scripts in MEMORY.md - a sweep found
old paths in six documents after the tool move, which the memory entry now warns
about.

Docs/release-checks.md

@@ -6,6 +6,8 @@ Record results in the table at the end of this file, with the date, the exact bu
 
 ## General checks (every release)
 
+0. **Blender pre-check (before the engine pass).** `Art/blender/site/site_assembly.py` raycasts both sidewalks and the designated crossing on a 1 m grid and reports holes and step heights. It is evidence, not the check: the engine traversal below is still required.
+
 1. **Fresh checkout builds.** Clone into a clean directory, `git lfs pull`, build and package using only the documented external engine installation. No machine-specific paths, no uncommitted steps.
 2. **No packaging errors.** The packaged build launches, reaches gameplay, and quits cleanly. Logs contain no missing-asset, missing-map, or shader-compile errors.
 3. **Licensing.** Every new asset has provenance in `THIRD_PARTY_NOTICES.md`, or is recorded as unresolved and kept out of the build.