Polish version notifications and sync changelog canvas (#21) (#25)

Reworks the daily version bump workflow to:
- Pull merged PR titles via gh CLI instead of raw commit messages
- Post a polished, non-technical channel message with a link to the
  changelog canvas
- Prepend the new version entry to the Slack canvas via canvases.edit
  API so the canvas stays in sync automatically

Channel message format:
  "After-Hours Scheduler has been updated to vXXXX.XX.XX
   Here's a brief summary of what changed:
   • ...
   Click here to read the full changelog"

.github/workflows/deploy-notify.yml

@@ -13,6 +13,8 @@ permissions:
 jobs:
   notify:
     runs-on: ubuntu-latest
+    env:
+      GH_TOKEN: ${{ github.token }}
     steps:
       - uses: actions/checkout@v4
         with:
@@ -30,53 +32,106 @@ jobs:
             echo "skip=false" >> "$GITHUB_OUTPUT"
           fi
 
-      - name: Check for changes since last version tag
+      - name: Collect merged PRs since last version
         if: steps.dst.outputs.skip != 'true'
         id: changes
         run: |
           LAST_TAG=$(git tag -l 'v*' --sort=-v:refname | head -1)
+
           if [ -z "$LAST_TAG" ]; then
-            echo "No previous version tag — using full history"
+            echo "No previous version tag"
-            COMMITS=$(git log --oneline --pretty=format:"%s")
+            echo "has_changes=false" >> "$GITHUB_OUTPUT"
-          else
+            exit 0
-            COMMITS=$(git log "$LAST_TAG"..HEAD --oneline --pretty=format:"%s")
           fi
 
-          if [ -z "$COMMITS" ]; then
+          LAST_TAG_DATE=$(git log -1 --format=%aI "$LAST_TAG")
-            echo "No new commits since $LAST_TAG"
+          PRS=$(gh pr list --state merged --json number,title,mergedAt \
+            --jq "sort_by(.number) | .[] | select(.mergedAt > \"$LAST_TAG_DATE\")")
+
+          if [ -z "$PRS" ]; then
+            echo "No PRs merged since $LAST_TAG"
             echo "has_changes=false" >> "$GITHUB_OUTPUT"
             exit 0
           fi
 
           echo "has_changes=true" >> "$GITHUB_OUTPUT"
 
-          # Build bullet list from commit messages, skip merge commits
+          VERSION="v$(TZ=America/New_York date +%Y.%m.%d)"
-          BULLET_LIST=$(echo "$COMMITS" | grep -v "^Merge" | sed 's/^/• /')
-          {
-            echo "bullets<<ENDOFBULLETS"
-            echo "$BULLET_LIST"
-            echo "ENDOFBULLETS"
-          } >> "$GITHUB_OUTPUT"
-
-          # Date-based version
-          VERSION="v$(date +%Y.%m.%d)"
           echo "version=$VERSION" >> "$GITHUB_OUTPUT"
 
+          # Build bullet lists from PR titles
+          TITLES=$(gh pr list --state merged --json number,title,mergedAt \
+            --jq "sort_by(.number) | .[] | select(.mergedAt > \"$LAST_TAG_DATE\") | .title")
+
+          {
+            echo "slack_bullets<<ENDSLACK"
+            echo "$TITLES" | sed 's/ *(#[0-9]*)//g; s/^/• /'
+            echo "ENDSLACK"
+          } >> "$GITHUB_OUTPUT"
+
+          {
+            echo "canvas_bullets<<ENDCANVAS"
+            gh pr list --state merged --json number,title,mergedAt \
+              --jq "sort_by(.number) | .[] | select(.mergedAt > \"$LAST_TAG_DATE\") | \"* \(.title) (PR #\(.number))\"" \
+              | sed 's/ *(\(#[0-9]*\))\( (PR\)/ \2/; s/) (PR / (PR /'
+            echo "ENDCANVAS"
+          } >> "$GITHUB_OUTPUT"
+
       - name: Create version tag
-        if: steps.dst.outputs.skip != 'true' && steps.changes.outputs.has_changes == 'true'
+        if: steps.changes.outputs.has_changes == 'true'
         run: |
           git tag ${{ steps.changes.outputs.version }}
           git push origin ${{ steps.changes.outputs.version }}
 
+      - name: Update changelog canvas
+        if: steps.changes.outputs.has_changes == 'true'
+        env:
+          SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
+          CANVAS_ID: ${{ secrets.SLACK_CANVAS_ID }}
+          SECTION_ID: ${{ secrets.SLACK_CANVAS_INTRO_SECTION }}
+          VERSION: ${{ steps.changes.outputs.version }}
+          CANVAS_BULLETS: ${{ steps.changes.outputs.canvas_bullets }}
+        run: |
+          TODAY=$(TZ=America/New_York date +%Y-%m-%d)
+          MARKDOWN=$(printf "---\n\n## %s — %s\n\n%s" "$VERSION" "$TODAY" "$CANVAS_BULLETS")
+
+          RESPONSE=$(curl -s -X POST https://slack.com/api/canvases.edit \
+            -H "Authorization: Bearer $SLACK_BOT_TOKEN" \
+            -H "Content-Type: application/json" \
+            -d "$(jq -n \
+              --arg canvas_id "$CANVAS_ID" \
+              --arg section_id "$SECTION_ID" \
+              --arg markdown "$MARKDOWN" \
+              '{
+                canvas_id: $canvas_id,
+                changes: [{
+                  operation: "insert_after",
+                  section_id: $section_id,
+                  document_content: {
+                    type: "markdown",
+                    markdown: $markdown
+                  }
+                }]
+              }')")
+
+          echo "$RESPONSE" | jq .
+          if [ "$(echo "$RESPONSE" | jq -r .ok)" != "true" ]; then
+            echo "::warning::Canvas update failed: $(echo "$RESPONSE" | jq -r .error)"
+          fi
+
       - name: Post to Slack
-        if: steps.dst.outputs.skip != 'true' && steps.changes.outputs.has_changes == 'true'
+        if: steps.changes.outputs.has_changes == 'true'
         env:
           SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
           SLACK_CHANNEL_ID: ${{ secrets.SLACK_CHANNEL_ID }}
+          CANVAS_ID: ${{ secrets.SLACK_CANVAS_ID }}
           VERSION: ${{ steps.changes.outputs.version }}
-          BULLETS: ${{ steps.changes.outputs.bullets }}
+          SLACK_BULLETS: ${{ steps.changes.outputs.slack_bullets }}
         run: |
-          TEXT=$(printf ":rocket: *%s deployed*\n\n%s" "$VERSION" "$BULLETS")
+          CANVAS_URL="https://app.slack.com/docs/F0B13V3EBUN"
+          TEXT=$(printf "*After-Hours Scheduler has been updated to %s*\n\nHere's a brief summary of what changed:\n%s\n\n<%s|Click here to read the full changelog>" \
+            "$VERSION" "$SLACK_BULLETS" "$CANVAS_URL")
+
           curl -s -X POST https://slack.com/api/chat.postMessage \
             -H "Authorization: Bearer $SLACK_BOT_TOKEN" \
             -H "Content-Type: application/json" \