chore: rename integration branch from beta to dev

Update CI/CD configuration, documentation, and scripts to use dev as the
primary integration branch instead of beta. Changes include GitHub Actions
workflow triggers, semantic-release configuration, and all relevant
documentation and helper scripts.

scripts/bump-version.sh

@@ -4,7 +4,7 @@
 #
 # Releases are now automated via semantic-release:
 #   - Merge to main  → stable release (npm @latest)
-#   - Merge to beta  → beta release (npm @beta)
+#   - Merge to dev   → dev release (npm @dev)
 #
 # Version is determined automatically from conventional commits:
 #   - feat: commit   → MINOR bump (5.0.2 → 5.1.0)
@@ -23,7 +23,7 @@ echo "============================================================="
 echo "[!] DEPRECATED: This script is for emergency use only."
 echo ""
 echo "    Releases are now automated via semantic-release."
-echo "    Simply merge to 'main' or 'beta' branch."
+echo "    Simply merge to 'main' or 'dev' branch."
 echo ""
 echo "    Version is determined from conventional commits:"
 echo "      feat: commit   -> MINOR (5.0.2 -> 5.1.0)"