feat(release): simplify dev versioning with stable base

- Remove dev branch from semantic-release (main only)
- Add dev-release.yml: simple X.Y.Z-dev.N bump workflow
- Update sync workflow: handle merge conflicts for version files
- Update release.yml: trigger only on main branch

Dev versions now stay at {stable}-dev.N until merged to main.
PR merge commit type (feat/fix) determines actual version bump.

.github/workflows/sync-dev-after-release.yml

@@ -31,5 +31,21 @@ jobs:
         run: |
           git fetch origin main dev
           git checkout dev
-          git merge origin/main --no-edit -m "chore(sync): merge main into dev after release [skip ci]"
+
+          # Attempt merge, handle version conflicts by taking main's versions
+          if ! git merge origin/main --no-edit -m "chore(sync): merge main into dev after release [skip ci]"; then
+            echo "Merge conflicts detected, resolving version files..."
+
+            # For version files, take main's version (new stable base)
+            for file in VERSION package.json installers/install.sh installers/install.ps1 CHANGELOG.md; do
+              if git diff --name-only --diff-filter=U | grep -q "^${file}$"; then
+                git checkout --theirs "$file"
+                git add "$file"
+              fi
+            done
+
+            # Complete the merge
+            git commit --no-edit
+          fi
+
           git push origin dev