chore: add direnv .envrc for per-repo nix shell

Auto-loads the repo's own flake devshell on cd via direnv.
No-op for non-Nix users (direnv just isn't installed). Ignore
the .direnv/ eval cache.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

flake.nix

@@ -71,7 +71,6 @@
             gotools
             ffmpeg
             git
-            tea
             gnumake
             bashInteractive
             shellcheck

wrappers/consumers.txt

@@ -3,4 +3,3 @@
 # wrappers/ changes. Add a repo here AND grant the sync bot write access to it.
 ShadowsOverWestgate/sow-module
 ShadowsOverWestgate/sow-topdata
-ShadowsOverWestgate/sow-assets-manifest