feat(nn): entry–secret N:N, unique secret names, web unlink

Bump secrets-mcp to 0.3.8 (tag 0.3.7 already used).

- Junction table entry_secrets; secrets user-scoped with type
- Per-user unique secrets.name; link_secret_names on add
- Manual migrations + migrate script; MCP/tool and Web updates

Made-with: Cursor

Cargo.lock

@@ -1968,7 +1968,7 @@ dependencies = [
 
 [[package]]
 name = "secrets-mcp"
-version = "0.3.7"
+version = "0.3.8"
 dependencies = [
  "anyhow",
  "askama",