Update CLAUDE.md and download script for proxy/offline builds

Add proxy/offline build instructions to CLAUDE.md referencing the
download script. Add clipp and snappy dependencies to the download
script for complete host test coverage.

Author: claude

CLAUDE.md

@@ -33,6 +33,20 @@ wget http://security.ubuntu.com/ubuntu/pool/universe/n/ncurses/libtinfo5_6.3-2ub
 sudo apt install -y ./libtinfo5_6.3-2ubuntu0.1_amd64.deb
 ```
 
+## Proxy/Offline Builds
+
+If bazel cannot download dependencies due to proxy authentication issues, use the download script to pre-populate the cache:
+
+```
+bash utils/download_bazel_deps.sh
+```
+
+Then run bazel with the cache flags:
+
+```
+tools/bazel test --config=host //:host --repository_cache=/tmp/repo_cache --distdir=/tmp/bazel_cache
+```
+
 ## Development Commands
 
 ### Command line interaction with devices

utils/download_bazel_deps.sh

@@ -81,6 +81,10 @@ download_and_cache "https://github.com/fmtlib/fmt/archive/5.0.0.tar.gz" \
 download_and_cache "https://github.com/Naios/function2/archive/7cd95374b0f1c941892bfc40f0ebb6564d33fdb9.zip" \
     "f2127da1c83d1c3dea8a416355a7cbb4e81fe55cf27ac9ef712d0554a3b745b6"
 
+download_and_cache "https://github.com/muellan/clipp/archive/2c32b2f1f7cc530b1ec1f62c92f698643bb368db.zip"
+
+download_and_cache "https://github.com/google/snappy/archive/1.1.7.tar.gz"
+
 # System dependencies (Ubuntu 24.04 needs libtinfo5 from older package)
 if ! ldconfig -p | grep -q libtinfo.so.5; then
     echo "Installing libtinfo5..."