fix: make build-slides.sh work with Docker marp by using temp directory with proper permissions

- Process each slide individually to avoid Docker --output flag issues
- Use a temp directory with 777 permissions for Docker to write to
- Copy generated files to final output directory after build
- Both marp-cli and mermaid injection now work properly with Docker

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

build-slides.sh

@@ -3,7 +3,6 @@ set -euo pipefail
 
 REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 OUTPUT_DIR="$REPO_ROOT/slides"
-mkdir -p "$OUTPUT_DIR"
 
 # Find all markdown files with marp: true frontmatter
 SLIDES=()
@@ -19,20 +18,32 @@ fi
 echo "Found ${#SLIDES[@]} presentation(s):"
 printf '  %s\n' "${SLIDES[@]}"
 
+# Create temp output directory for Docker
+TEMP_OUTPUT=$(mktemp -d)
+chmod 777 "$TEMP_OUTPUT"
+trap "rm -rf '$TEMP_OUTPUT'" EXIT
+
 if command -v marp &>/dev/null; then
   marp --html --output "$OUTPUT_DIR/" "${SLIDES[@]}"
 else
   echo "marp not found locally — using Docker (marpteam/marp-cli)..."
-  REL_SLIDES=()
-  for f in "${SLIDES[@]}"; do
-    REL_SLIDES+=("${f#"$REPO_ROOT"/}")
-  done
+  # Process each slide individually in Docker
+  for slide in "${SLIDES[@]}"; do
+    REL_SLIDE="${slide#${REPO_ROOT}/}"
+    BASENAME=$(basename "${slide%.*}")
     docker run --rm \
       -v "$REPO_ROOT":/home/marp/app:ro \
-    -v "$OUTPUT_DIR":/home/marp/output \
-    marpteam/marp-cli --html --output /home/marp/output "${REL_SLIDES[@]}"
+      -v "$TEMP_OUTPUT":/home/marp/output \
+      marpteam/marp-cli --html --output "/home/marp/output/${BASENAME}.html" "$REL_SLIDE"
+  done
 fi
 
+# Ensure output directory exists
+mkdir -p "$OUTPUT_DIR"
+
+# Copy generated HTML files to final output directory
+cp "$TEMP_OUTPUT"/*.html "$OUTPUT_DIR/" 2>/dev/null || true
+
 # Inject mermaid.js into any HTML that contains mermaid code blocks.
 # Marp emits fenced mermaid blocks as <pre><code class="language-mermaid">.
 # The script finds those elements, replaces them with <div class="mermaid">,