Check README and docs links and anchors in CI

.github/workflows/links.yml

@@ -0,0 +1,21 @@
+name: Links
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  links:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Check links and anchors in README and docs (offline)
+        uses: lycheeverse/lychee-action@v2
+        with:
+          args: --offline --include-fragments --no-progress README.md 'docs/**/*.md'
+          fail: true

docs/readme-details.md

@@ -101,7 +101,7 @@ python3 -m venv /tmp/grainx-render-venv && /tmp/grainx-render-venv/bin/pip insta
 /tmp/grainx-render-venv/bin/python demos/capture_tui.py target/debug/grainx /tmp/tui.raw /tmp/tui.txt 5 110 50
 ~~~
 
-See [demos/README.md](demos/README.md) and [demos/verification_2026-09-11.md](../demos/verification_2026-09-11.md)
+See [demos/README.md](../demos/README.md) and [demos/verification_2026-09-11.md](../demos/verification_2026-09-11.md)
 for the full commands, hashes, privacy review, and limitations.
 
 ## Performance and Microbenchmarks