docs: add Sparkle HTML release notes

scripts/changelog-to-html.sh

@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+VERSION=${1:-}
+CHANGELOG_FILE=${2:-}
+
+if [[ -z "$VERSION" ]]; then
+  echo "Usage: $0 <version> [changelog_file]" >&2
+  exit 1
+fi
+
+SCRIPT_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+if [[ -z "$CHANGELOG_FILE" ]]; then
+  if [[ -f "$SCRIPT_DIR/../CHANGELOG.md" ]]; then
+    CHANGELOG_FILE="$SCRIPT_DIR/../CHANGELOG.md"
+  elif [[ -f "CHANGELOG.md" ]]; then
+    CHANGELOG_FILE="CHANGELOG.md"
+  elif [[ -f "../CHANGELOG.md" ]]; then
+    CHANGELOG_FILE="../CHANGELOG.md"
+  else
+    echo "Error: Could not find CHANGELOG.md" >&2
+    exit 1
+  fi
+fi
+
+if [[ ! -f "$CHANGELOG_FILE" ]]; then
+  echo "Error: Changelog file '$CHANGELOG_FILE' not found" >&2
+  exit 1
+fi
+
+extract_version_section() {
+  local version=$1
+  local file=$2
+  awk -v version="$version" '
+    BEGIN { found=0 }
+    /^## / {
+      if ($0 ~ "^##[[:space:]]+" version "([[:space:]].*|$)") { found=1; next }
+      if (found) { exit }
+    }
+    found { print }
+  ' "$file"
+}
+
+markdown_to_html() {
+  local text=$1
+  text=$(echo "$text" | sed 's/^### \(.*\)$/<h3>\1<\/h3>/')
+  text=$(echo "$text" | sed 's/^## \(.*\)$/<h2>\1<\/h2>/')
+  text=$(echo "$text" | sed 's/^- \*\*\([^*]*\)\*\*\(.*\)$/<li><strong>\1<\/strong>\2<\/li>/')
+  text=$(echo "$text" | sed 's/^- \([^*].*\)$/<li>\1<\/li>/')
+  text=$(echo "$text" | sed 's/\*\*\([^*]*\)\*\*/<strong>\1<\/strong>/g')
+  text=$(echo "$text" | sed 's/`\([^`]*\)`/<code>\1<\/code>/g')
+  text=$(echo "$text" | sed 's/\[\([^]]*\)\](\([^)]*\))/<a href="\2">\1<\/a>/g')
+  echo "$text"
+}
+
+version_content=$(extract_version_section "$VERSION" "$CHANGELOG_FILE")
+if [[ -z "$version_content" ]]; then
+  echo "<h2>Clawdis $VERSION</h2>"
+  echo "<p>Latest Clawdis update.</p>"
+  echo "<p><a href=\"https://github.com/steipete/clawdis/blob/main/CHANGELOG.md\">View full changelog</a></p>"
+  exit 0
+fi
+
+echo "<h2>Clawdis $VERSION</h2>"
+
+in_list=false
+while IFS= read -r line; do
+  if [[ "$line" =~ ^- ]]; then
+    if [[ "$in_list" == false ]]; then
+      echo "<ul>"
+      in_list=true
+    fi
+    markdown_to_html "$line"
+  else
+    if [[ "$in_list" == true ]]; then
+      echo "</ul>"
+      in_list=false
+    fi
+    if [[ -n "$line" ]]; then
+      markdown_to_html "$line"
+    fi
+  fi
+done <<< "$version_content"
+
+if [[ "$in_list" == true ]]; then
+  echo "</ul>"
+fi
+
+echo "<p><a href=\"https://github.com/steipete/clawdis/blob/main/CHANGELOG.md\">View full changelog</a></p>"