fix: update post-create.sh for current build system and fix unbound variables (#3304)

Signed-off-by: Keiven Chang <keivenchang@users.noreply.github.com>

.devcontainer/post-create.sh

@@ -63,7 +63,7 @@ mkdir -p $CARGO_TARGET_DIR
 uv pip uninstall --yes ai-dynamo ai-dynamo-runtime 2>/dev/null || true
 
 # Build project, with `dev` profile it will be saved at $CARGO_TARGET_DIR/debug
-cargo build --locked --profile dev --features mistralrs
+cargo build --locked --profile dev --features dynamo-llm/block-manager
 
 # install the python bindings
 
@@ -82,13 +82,13 @@ cargo build --locked --profile dev --features mistralrs
 # installs overall python packages, grabs binaries from .build/target/debug
 cd $DYNAMO_HOME && retry env DYNAMO_BIN_PATH=$CARGO_TARGET_DIR/debug uv pip install -e .
 
+{ set +x; } 2>/dev/null
+
 echo -e "\n" >> ~/.bashrc
 echo "# === This section is generated by the post-create.sh script ===" >> ~/.bashrc
 
-{ set +x; } 2>/dev/null
-
 # Check if PYTHONPATH is already set in environment
-if [ -n "$PYTHONPATH" ]; then
+if [ -n "${PYTHONPATH:-}" ]; then
     # PYTHONPATH exists, replace /workspace with $DYNAMO_HOME
     export PYTHONPATH=$(echo "$PYTHONPATH" | sed "s|/workspace|$DYNAMO_HOME|g")
     # Also add to .bashrc for persistence
@@ -122,13 +122,13 @@ fi
 # Unset empty tokens/variables to avoid issues with authentication and SSH
 if ! grep -q "# Unset empty tokens" ~/.bashrc; then
     echo -e "\n# Unset empty tokens and environment variables" >> ~/.bashrc
-    echo '[ -z "$HF_TOKEN" ] && unset HF_TOKEN' >> ~/.bashrc
-    echo '[ -z "$GITHUB_TOKEN" ] && unset GITHUB_TOKEN' >> ~/.bashrc
-    echo '[ -z "$SSH_AUTH_SOCK" ] && unset SSH_AUTH_SOCK' >> ~/.bashrc
+    echo '[ -z "${HF_TOKEN:-}" ] && unset HF_TOKEN' >> ~/.bashrc
+    echo '[ -z "${GITHUB_TOKEN:-}" ] && unset GITHUB_TOKEN' >> ~/.bashrc
+    echo '[ -z "${SSH_AUTH_SOCK:-}" ] && unset SSH_AUTH_SOCK' >> ~/.bashrc
 fi
 
 # Check SSH agent forwarding status
-if [ -n "$SSH_AUTH_SOCK" ]; then
+if [ -n "${SSH_AUTH_SOCK:-}" ]; then
     if ssh-add -l > /dev/null 2>&1; then
         echo "SSH agent forwarding is working - found $(ssh-add -l | wc -l) key(s):"
         ssh-add -l