ci: bump dtolnay/rust-toolchain from fa04a1451ff1842e2626ccb99004d0195b455a88 to 2c7215f132e9ebf062739d9130488b56d53c060c #1129

	# SPDX-License-Identifier: MPL-2.0
	# Stdlib naming convention check
	#
	# Enforces: stdlib/*.affine filenames are lowercase.
	#
	# Why: a 2026-04 transition introduced lowercase versions alongside
	# pre-existing PascalCase ones (Math.affine + math.affine etc.).
	# This caused a permanent case-collision on case-insensitive
	# filesystems (Windows NTFS, default macOS). Pinning the convention
	# at lowercase prevents the duplicate-file regression.

	name: Stdlib Naming Convention
	on:
	push:
	branches: [main]
	pull_request:
	branches: [main]
	permissions:
	contents: read
	# Actions concurrency pool. Applied only to read-only check workflows
	# (no publish/mutation), so cancelling a superseded run is always safe.
	concurrency:
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: true
	jobs:
	enforce-lowercase-stdlib:
	runs-on: ubuntu-latest
	timeout-minutes: 10
	steps:
	- uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
	- name: Enforce lowercase .affine filenames in stdlib/
	run: \|
	BAD=$(find stdlib -maxdepth 1 -type f -name '*.affine' \| grep -E '/stdlib/[A-Z]' \|\| true)
	if [ -n "$BAD" ]; then
	echo "❌ stdlib/ requires lowercase .affine filenames. Found:"
	echo "$BAD"
	echo ""
	echo "Convention: stdlib/foo.affine, not stdlib/Foo.affine."
	echo "PascalCase files cause case-collision on case-insensitive"
	echo "filesystems (Windows NTFS, default macOS HFS+/APFS) when a"
	echo "lowercase counterpart also exists in the tree."
	exit 1
	fi
	echo "✅ stdlib/ filenames lowercase OK"

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