Normalise line endings to LF

Author: celticht32

.gitattributes

@@ -0,0 +1,56 @@
+# .gitattributes — line-ending normalisation
+#
+# WHY THIS EXISTS
+# ===============
+# `git add` on Windows warned "LF will be replaced by CRLF the next time Git touches
+# it" for every file in a batch, which means core.autocrlf is rewriting on checkout.
+# Git stores LF in the repository either way, so nothing is corrupt — but the
+# consequences are worth removing:
+#
+#   * The working tree stops matching the repository byte-for-byte, so any hash or
+#     byte comparison between a Windows checkout and a Linux CI runner disagrees for
+#     reasons that have nothing to do with content. That is exactly the kind of noise
+#     that hides a real difference: four files in this repository were once a revision
+#     behind, and finding that meant hashing every .py file against a known-good copy.
+#   * A file that must not carry CRLF eventually does. A shell script with CRLF fails
+#     in a container with "\r: command not found", and a here-doc or a signature block
+#     with a stray \r fails in ways that read as a logic bug.
+#
+# eol=lf rather than bare `text=auto`: this pins LF in the WORKING TREE too, on every
+# platform, so a Windows checkout is byte-identical to what CI tests. Every editor
+# that matters handles LF on Windows.
+#
+# AFTER ADDING THIS, RENORMALISE ONCE:
+#     git add --renormalize .
+#     git status          # expect nothing, or line-ending-only changes
+#     git commit -m "Normalise line endings to LF"
+* text=auto eol=lf
+
+# Generated. Kept out of diffs and out of language statistics; it is still committed,
+# because without it CI resolves dependencies fresh on every run and the build is not
+# reproducible.
+uv.lock -diff linguist-generated=true
+
+# Binary. Never transformed, never diffed as text.
+*.png  binary
+*.jpg  binary
+*.jpeg binary
+*.gif  binary
+*.ico  binary
+*.pdf  binary
+*.docx binary
+*.pptx binary
+*.xlsx binary
+*.zip  binary
+*.whl  binary
+*.gz   binary
+*.p12  binary
+*.pfx  binary
+
+# Vendored browser libraries for the console: shipped as-is, excluded from language
+# statistics so the repository does not read as mostly JavaScript.
+gui/static/vendor/** linguist-vendored=true
+
+# Documentation figures are generated by docs/make_arch_diagrams.py and the Mermaid
+# sources in docs/diagrams-src; diffing them as text is meaningless.
+docs/diagrams/** binary