feat(sprint-5.5): store block metadata (version, changelog) in PostgreSQL

- Prisma schema: added `changelog Json @default("[]")` to Block model
- Migration: 20260324141120_add_changelog_field
- Seed: 8 blocks with actual versions (v1.0–v1.2) and changelog entries
- API: PATCH /blocks/by-path accepts changelog field
- CORS: accept any localhost port (regex pattern)
- BlockChangelog component: renders version history from API or fallback
- BlockMetaBar: loads changelog from API, passes to BlockChangelog
  - Removed "API офлайн" text, replaced with subtle gray dot
  - Added defaultChangelog prop for offline fallback
- Block pages: removed hardcoded changelog JSX, use defaultChangelog prop
- Updated SPRINTS.md with completed tasks

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/components/ui/BlockChangelog.tsx

@@ -0,0 +1,41 @@
+"use client";
+
+export interface ChangelogEntry {
+  version: string;
+  date: string;
+  changes: string[];
+}
+
+interface BlockChangelogProps {
+  changelog: ChangelogEntry[];
+}
+
+export function BlockChangelog({ changelog }: BlockChangelogProps) {
+  if (!changelog || changelog.length === 0) return null;
+
+  return (
+    <section className="space-y-3">
+      <h2 className="font-semibold text-base" style={{ color: "var(--bb-text)" }}>
+        История версий
+      </h2>
+      <div className="space-y-2 text-sm" style={{ color: "var(--bb-text-muted)" }}>
+        {changelog.map((entry) => (
+          <div
+            key={entry.version}
+            className="p-3 rounded-lg"
+            style={{ background: "var(--bb-sidebar-bg)", border: "1px solid var(--bb-border)" }}
+          >
+            <p className="font-semibold text-xs mb-1" style={{ color: "var(--bb-text)" }}>
+              {entry.version} — {entry.date}
+            </p>
+            <ul className="list-disc list-inside space-y-0.5 text-xs">
+              {entry.changes.map((change, i) => (
+                <li key={i}>{change}</li>
+              ))}
+            </ul>
+          </div>
+        ))}
+      </div>
+    </section>
+  );
+}