chore(3.0.0-rc.1): bump version to 3.0.0-rc.1, close resolved issues, update CHANGELOG

- package.json: 2.9.5 → 3.0.0-rc.1
- docs/openapi.yaml: version → 3.0.0-rc.1
- CHANGELOG.md: add [3.0.0-rc.1] section with all batch1-3 fixes
- scripts/check-docs-sync.mjs: isSemver now accepts pre-release versions (X.Y.Z-prerelease.N)

Closed issues: #489, #492, #510, #513, #520, #521, #522, #525, #527, #532
RC versioning: rc.1 → rc.2 → rc.N on each VPS deploy until v3.0.0 is approved

scripts/check-docs-sync.mjs

@@ -48,7 +48,8 @@ function extractChangelogSections(content) {
 }
 
 function isSemver(value) {
-  return /^\d+\.\d+\.\d+$/.test(value);
+  // Accept X.Y.Z and X.Y.Z-prerelease.N (e.g. 3.0.0-rc.1, 3.0.0-beta.2)
+  return /^\d+\.\d+\.\d+(-[a-zA-Z0-9.]+)?$/.test(value);
 }
 
 let hasFailure = false;