ci: adopt linecheck to enforce per-file line limits

.github/workflows/linecheck.yml

@@ -0,0 +1,16 @@
+name: linecheck
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: tupe12334/linecheck@main
+        with:
+          version: "1.2.0"

linecheck.yml

@@ -0,0 +1,20 @@
+# yaml-language-server: $schema=https://raw.githubusercontent.com/tupe12334/linecheck/main/schema/linecheck.schema.json
+
+rules:
+  - pattern: "tests/**/*.rs"
+    warn: 400
+    warn_message: "Integration test file is getting long — consider splitting by command"
+    error: 1000
+    error_message: "Test file is too large to navigate — split before merging"
+  - pattern: "**/*"
+    warn: 200
+    warn_message: "Getting long — consider splitting"
+    error: 400
+    error_message: "File exceeds the hard limit — split before merging"
+
+exclude:
+  - "Cargo.lock"
+  - "CHANGELOG.md"
+  - "**/package-lock.json"
+  - "**/pnpm-lock.yaml"
+  - "assets/**"