fix: docs/COMMAND-REGISTRY.json check fails on fresh Windows clone (missing .gitattributes) (#2437)

* fix: add .gitattributes to force LF line endings for text files

npm run command-registry:check (part of npm test) fails on a fresh clone
on Windows with the common core.autocrlf=true setting: git checks out
docs/COMMAND-REGISTRY.json with CRLF, but generate-command-registry.js
always writes LF, so the strict string comparison in checkRegistry()
never matches. Forcing LF via .gitattributes makes checkouts consistent
across platforms regardless of a contributor's local autocrlf setting.

* fix: normalize CRLF line endings to LF per .gitattributes

pyproject.toml, src/llm/__init__.py, src/llm/prompt/builder.py,
src/llm/providers/claude.py, and tests/test_builder.py had CRLF line
endings committed to the repo, inconsistent with the rest of the
codebase. Renormalized via 'git add --renormalize .' now that
.gitattributes enforces eol=lf.

---------

Co-authored-by: Affaan Mustafa <me@affaanmustafa.com>

.gitattributes

@@ -0,0 +1,7 @@
+* text=auto eol=lf
+
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.ico binary