Fix zk installation URL to use versioned release filename

The zk GitHub releases use versioned filenames (zk-v0.15.2-linux-amd64.tar.gz),
not the generic pattern. Use the GitHub API to find the correct download URL.

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

Dockerfile

@@ -45,8 +45,10 @@ RUN curl -sL https://raw.githubusercontent.com/denisidoro/navi/master/scripts/in
     || echo "navi installation skipped (offline build)"
 
 # Install zk (wiki browser with [[wiki-links]], fzf search, backlinks)
-RUN curl -sL https://github.com/zk-org/zk/releases/latest/download/zk-linux-amd64.tar.gz \
-    | tar xz -C /usr/local/bin/ 2>/dev/null \
+RUN ZK_URL=$(curl -sL https://api.github.com/repos/zk-org/zk/releases/latest \
+    | grep -o '"browser_download_url": "[^"]*linux-amd64[^"]*"' \
+    | head -1 | cut -d'"' -f4) \
+    && if [ -n "$ZK_URL" ]; then curl -sL "$ZK_URL" | tar xz -C /usr/local/bin/; fi \
     || echo "zk installation skipped (offline build)"
 
 # Create data directory and set permissions