feat(ci): per-product codeblock testing with shared content resolution

.github/scripts/resolve-shared-content.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# Resolve shared content files to their consuming product pages.
+#
+# Usage:
+#   echo "content/shared/foo.md" | ./resolve-shared-content.sh
+#   ./resolve-shared-content.sh < changed_files.txt
+#   ./resolve-shared-content.sh changed_files.txt
+#
+# For shared files (content/shared/*), finds all pages with matching
+# `source:` frontmatter and outputs those instead. Non-shared files
+# pass through unchanged.
+
+set -euo pipefail
+
+# Read input from file argument or stdin
+if [[ $# -gt 0 && -f "$1" ]]; then
+  INPUT=$(cat "$1")
+else
+  INPUT=$(cat)
+fi
+
+# Process each file
+while IFS= read -r file; do
+  [[ -z "$file" ]] && continue
+
+  if [[ "$file" == content/shared/* ]]; then
+    # Extract the shared path portion (e.g., /shared/influxdb3-cli/foo.md)
+    SHARED_PATH="${file#content}"
+
+    # Find all files that source this shared content
+    # The source frontmatter looks like: source: /shared/path/to/file.md
+    CONSUMERS=$(grep -rl "^source: ${SHARED_PATH}$" content/ 2>/dev/null | grep -v '^content/shared/' || true)
+
+    if [[ -n "$CONSUMERS" ]]; then
+      echo "$CONSUMERS"
+    else
+      # No consumers found - output the shared file itself
+      # (Vale can still lint it with default config)
+      echo "$file"
+    fi
+  else
+    # Non-shared file - pass through
+    echo "$file"
+  fi
+done <<< "$INPUT" | sort -u