fix(docker): include Cargo.lock for reproducible builds

The .dockerignore was excluding Cargo.lock which is needed for
reproducible Docker builds.

Terraphim AI

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: AlexMikhalev

.dockerignore

@@ -17,7 +17,8 @@ examples/
 # Dependencies and caches
 node_modules/
 target/
-Cargo.lock
+# Note: Cargo.lock is needed for reproducible Docker builds
+# Cargo.lock
 
 # Development and test files
 tests/