ci: dedupe permissions block in lint.yml

Copilot Autofix added a permissions block before `concurrency`
without noticing 0cc5d11 had already added one after `concurrency`.
Remove the redundant second block; Copilot's position (before
concurrency) is the more conventional GitHub Actions placement.

https://claude.ai/code/session_01XE1bMoQ5BjCvgi1iLGKKhG

Author: claude

.github/workflows/lint.yml

@@ -29,9 +29,6 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
   cancel-in-progress: true
 
-permissions:
-  contents: read
-
 jobs:
   lint:
     name: Lint & Type Check