Dockerfile: copy in the logo files the directory crate builds in (#217)

ipx depends on ipx-directory, whose site.rs include_bytes! three files from web/ since #215;
Dockerfile.directory copied them and Dockerfile did not, so ipx's image stopped building.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -20,6 +20,8 @@ RUN mkdir -p crates/ipx/src crates/feed/src crates/directory/src \
     && rm -rf crates/ipx/src crates/feed/src crates/directory/src
 
 COPY crates ./crates
+# ipx builds the directory crate in, whose public pages serve these (#215).
+COPY web/logo.svg web/logo-dark.svg web/favicon.png ./web/
 # cargo skips a rebuild if mtimes look untouched; make sure it does not.
 RUN touch crates/ipx/src/main.rs crates/feed/src/lib.rs && cargo build --release --locked -p ipx