fix: use release-X.Y tag format to avoid semver range conflict

npm rejects tags like "v1.23" because they look like semver ranges.
Use "release-1.23" format instead.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: pcarleton

.github/workflows/main.yml

@@ -72,13 +72,14 @@ jobs:
                     echo "tag=--tag beta" >> $GITHUB_OUTPUT
                   # Check if this release is from a non-main branch (patch/maintenance release)
                   elif [[ "${{ github.event.release.target_commitish }}" != "main" ]]; then
-                    # Use major.minor as tag for old branch releases (e.g., "v1.23" for 1.23.x)
+                    # Use "release-X.Y" as tag for old branch releases (e.g., "release-1.23" for 1.23.x)
                     # npm tags are mutable pointers to versions (like "latest" pointing to 1.24.3).
-                    # Using "v1.23" means users can `npm install @modelcontextprotocol/sdk@v1.23`
+                    # Using "release-1.23" means users can `npm install @modelcontextprotocol/sdk@release-1.23`
                     # to get the latest patch on that minor version, and the tag updates if we
                     # release 1.23.2, 1.23.3, etc.
+                    # Note: Can't use "v1.23" because npm rejects tags that look like semver ranges.
                     MAJOR_MINOR=$(echo "$VERSION" | cut -d. -f1,2)
-                    echo "tag=--tag v${MAJOR_MINOR}" >> $GITHUB_OUTPUT
+                    echo "tag=--tag release-${MAJOR_MINOR}" >> $GITHUB_OUTPUT
                   else
                     echo "tag=" >> $GITHUB_OUTPUT
                   fi