fix: CRLF line endings in couchdb-init.sh, add .gitattributes

Shell scripts with CRLF line endings crash inside Linux containers with
'set: illegal option -' and 'command not found' errors.

- Strip CRLF -> LF in couchdb-init.sh
- Add .gitattributes to enforce LF on .sh, .yml, .ini, .md etc.
  so this never regresses on Windows checkouts

.gitattributes

@@ -0,0 +1,23 @@
+# Always checkout shell scripts with LF line endings (never CRLF)
+*.sh text eol=lf
+
+# Standard text files — auto normalize on checkout
+*.md text eol=lf
+*.yml text eol=lf
+*.yaml text eol=lf
+*.ini text eol=lf
+*.env text eol=lf
+*.json text eol=lf
+*.ts text eol=lf
+*.js text eol=lf
+*.mjs text eol=lf
+*.css text eol=lf
+
+# Binary files — no line ending conversion
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.ico binary
+*.woff2 binary
+*.woff binary