Normalise line endings to LF

spr had no .gitattributes at all, despite shipping ctrl/*.sh and generating
gen/<room>/ctrl/*.sh. A checkout on Windows/WSL rewrites those to CRLF, and a
shell script with CRLF fails as `bad interpreter: /usr/bin/env bash^M` — which
reads as a broken installer rather than a line-ending problem.

Copied verbatim from rig/.gitattributes and deliberately duplicated rather than
shared: rig/ has to carry its own so it survives being handed over alone.

No tracked file in either repo currently has CRLF, so `git add --renormalize .`
rewrote nothing. Landing it now, while that is true, keeps it off the diff of
whatever lands next.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitattributes

@@ -0,0 +1,27 @@
+# Copied verbatim from rig/.gitattributes, and deliberately duplicated rather
+# than shared: rig/ must carry its own so it survives being handed over on its
+# own, and spr had none at all despite shipping ctrl/*.sh and generating
+# gen/<room>/ctrl/*.sh.
+#
+# Line endings are normalised to LF in the repository and on checkout, on every
+# platform. Without this, a checkout on Windows/WSL rewrites files to CRLF and
+# every one of them shows up as modified without anyone having touched it.
+#
+# For the scripts it is not cosmetic: a shell script with CRLF fails on Linux
+# with `bad interpreter: /usr/bin/env bash^M`, which reads as a broken installer
+# rather than a line-ending problem — the worst possible first impression on a
+# machine where nothing has been proven yet.
+* text=auto eol=lf
+
+*.sh   text eol=lf
+*.py   text eol=lf
+*.env  text eol=lf
+*.yaml text eol=lf
+*.yml  text eol=lf
+
+# Never touch binaries.
+*.png binary
+*.jpg binary
+*.zip binary
+*.tar binary
+*.gz  binary