fix: scope changelog generation to only include commits since previous version

The script was using HEAD~50..HEAD which grabbed all recent commits
regardless of version boundaries, causing every entry to repeat items
from prior versions. Now finds the previous version bump commit and
uses it as the range start. Also regenerated CHANGELOG.md from scratch
to remove all accumulated duplicates (~1600 lines).

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

Author: jwaldrip

.github/scripts/generate-changelog.sh

@@ -29,18 +29,25 @@ if [ -z "$OLD_VERSION" ]; then
 	fi
 fi
 
-# Determine git range for commits
-# Get the last 50 commits and filter later
-GIT_RANGE="HEAD~50..HEAD"
+# Determine git range: from the last version bump commit to HEAD
+# This ensures each version only includes commits new since the previous release
+GIT_RANGE=""
+if [ -n "$OLD_VERSION" ]; then
+	# Find the commit that bumped TO the old version (e.g., "bump version X -> 1.16.0")
+	LAST_BUMP_COMMIT=$(git log --all --grep="bump version.*-> $OLD_VERSION" --format="%H" -1 2>/dev/null || true)
+	if [ -n "$LAST_BUMP_COMMIT" ]; then
+		GIT_RANGE="$LAST_BUMP_COMMIT..HEAD"
+	fi
+fi
+
+# Fallback: if no bump commit found, use all commits (first release scenario)
+if [ -z "$GIT_RANGE" ]; then
+	GIT_RANGE="HEAD"
+fi
 
 # Get commits for this path, excluding version bump commits and website changes
 COMMITS=$(git log $GIT_RANGE --pretty=format:"%h|%s|%an|%ad" --date=short -- "$PATH_DIR" ':!website' 2>/dev/null | grep -v "\[skip ci\]" | grep -v "chore(release):" | grep -v "chore(plugin): bump" || true)
 
-# If we still don't have commits, try without range limit
-if [ -z "$COMMITS" ]; then
-	COMMITS=$(git log --all --pretty=format:"%h|%s|%an|%ad" --date=short -- "$PATH_DIR" ':!website' 2>/dev/null | grep -v "\[skip ci\]" | grep -v "chore(release):" | grep -v "chore(plugin): bump" | head -20 || true)
-fi
-
 if [ -z "$COMMITS" ]; then
 	echo "No commits found for $PATH_DIR in range $GIT_RANGE"
 	exit 0
@@ -143,10 +150,11 @@ if [ -n "$OTHER" ]; then
 	} >>"$TEMP_FILE"
 fi
 
-# If existing changelog exists, append old entries (excluding the header)
+# If existing changelog exists, append old entries (excluding the header and [Unreleased] section)
 if [ -f "$CHANGELOG_FILE" ]; then
-	# Skip the first 6 lines (header) and append the rest
-	tail -n +7 "$CHANGELOG_FILE" >>"$TEMP_FILE" 2>/dev/null || true
+	# Skip header (first 6 lines), then strip any [Unreleased] section
+	# (its commits are now captured in the new version's range)
+	tail -n +7 "$CHANGELOG_FILE" 2>/dev/null | sed '/^## \[Unreleased\]/,/^## \[/{ /^## \[Unreleased\]/d; /^## \[/!d; }' >>"$TEMP_FILE" || true
 fi
 
 # Remove consecutive blank lines and ensure single trailing newline