chore: add gitignore, gitattributes, tool-versions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.gitattributes

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+# SPDX-License-Identifier: PMPL-1.0-or-later
+# RSR-compliant .gitattributes
+
+* text=auto eol=lf
+
+# Source
+*.rs    text eol=lf diff=rust
+*.ex    text eol=lf diff=elixir
+*.exs   text eol=lf diff=elixir
+*.jl    text eol=lf
+*.res   text eol=lf
+*.resi  text eol=lf
+*.ada   text eol=lf diff=ada
+*.adb   text eol=lf diff=ada
+*.ads   text eol=lf diff=ada
+*.hs    text eol=lf
+*.chpl  text eol=lf
+*.scm   text eol=lf
+*.a2ml  text eol=lf linguist-language=TOML
+*.ncl   text eol=lf
+*.nix   text eol=lf
+
+# Docs
+*.md    text eol=lf diff=markdown
+*.adoc  text eol=lf
+*.txt   text eol=lf
+
+# Data
+*.json  text eol=lf
+*.yaml  text eol=lf
+*.yml   text eol=lf
+*.toml  text eol=lf
+
+# Config
+.gitignore     text eol=lf
+.gitattributes text eol=lf
+justfile       text eol=lf
+Makefile       text eol=lf
+Containerfile  text eol=lf
+
+# Scripts
+*.sh   text eol=lf
+
+# Binary
+*.png   binary
+*.jpg   binary
+*.gif   binary
+*.pdf   binary
+*.woff2 binary
+*.zip   binary
+*.gz    binary
+
+# Lock files
+Cargo.lock  text eol=lf -diff
+flake.lock  text eol=lf -diff

.tool-versions

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+rust stable