feat: user-scoped history/delete/rollback, dashboard & login UI, ignore *.pem

- Filter history/rollback/delete by user_id in secrets-core
- MCP tools/web pass user context; dashboard refresh; favicon static
- .gitignore *.pem; vscode tasks tweaks
- clippy: collapse else-if in rollback latest-history branch

Made-with: Cursor

crates/secrets-core/src/service/update.rs

@@ -80,6 +80,7 @@ pub async fn run(
         &mut tx,
         db::EntrySnapshotParams {
             entry_id: row.id,
+            user_id: params.user_id,
             namespace: params.namespace,
             kind: params.kind,
             name: params.name,