fix: copy static directory in dockerfile for favicon build

the favicon.svg is embedded at compile time via include_str!(), so the
static/ directory needs to be present in the build context

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[e-mail]>

Dockerfile

···
 
 # Copy source code
 COPY src ./src
+COPY static ./static
 
 # Build for release
 RUN cargo build --release