feat: add semantic-release for automated versioning and help dialog

- Set up semantic-release with zero-touch CI pipeline on push to main
- Add version sync script to keep all package.json files and APP_VERSION
  constant in sync automatically
- Consolidate Docker publishing into single tag-triggered workflow that
  pushes to both Docker Hub and ghcr.io with semver tags
- Add help dialog with keyboard shortcuts, getting started guide, and
  resource links
- Sync all versions to 0.2.1 to match Docker Hub latest

scripts/sync-version.sh

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+# Syncs the version from semantic-release to all workspace package.json files
+# and the APP_VERSION constant in shared/constants.ts.
+#
+# Usage: ./scripts/sync-version.sh <version>
+# Example: ./scripts/sync-version.sh 1.2.3
+
+set -euo pipefail
+
+VERSION="${1:?Usage: sync-version.sh <version>}"
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+
+# All workspace package.json files to sync
+PACKAGES=(
+  "apps/web/package.json"
+  "apps/api/package.json"
+  "apps/docs/package.json"
+  "packages/shared/package.json"
+  "packages/image-engine/package.json"
+  "packages/ai/package.json"
+)
+
+for pkg in "${PACKAGES[@]}"; do
+  FILE="$ROOT/$pkg"
+  if [ -f "$FILE" ]; then
+    # Use node to update JSON cleanly (preserves formatting better than sed)
+    node -e "
+      const fs = require('fs');
+      const path = '$FILE';
+      const raw = fs.readFileSync(path, 'utf8');
+      const json = JSON.parse(raw);
+      json.version = '$VERSION';
+      fs.writeFileSync(path, JSON.stringify(json, null, 2) + '\n');
+    "
+    echo "  Updated $pkg -> $VERSION"
+  fi
+done
+
+# Update APP_VERSION in shared constants
+CONSTANTS="$ROOT/packages/shared/src/constants.ts"
+if [ -f "$CONSTANTS" ]; then
+  sed -i.bak "s/export const APP_VERSION = \".*\"/export const APP_VERSION = \"$VERSION\"/" "$CONSTANTS"
+  rm -f "$CONSTANTS.bak"
+  echo "  Updated APP_VERSION -> $VERSION"
+fi
+
+echo "All versions synced to $VERSION"