fix(ui): audit the silent catch blocks in lib/features; some hide failures from the user #1762

Problem

A rough classification of the 434 `catch` blocks in `lib` found about 46 empty ones and 10 that only return a fallback value. In `lib/features` the worst offenders are Mongo (15) and the workspace (15), then Redis, SQLite, connections and ERD. Most are harmless best-effort code (cache, history, probe). A few change what the user sees:

• `lib/features/mongodb/mongo_databases_view.dart:117`: a failed `listDatabases` (for example no permission) becomes an empty list with no message.
• `lib/features/connections/sqlite_connection_form.dart:141`: `catch (_) {}` around choosing a file.
• Query and CLI history (`mongo_query_workspace.dart:206`, `redis_cli_workspace.dart:290`): lost silently, no log.

The classification is automatic and approximate; each site needs a look.

Proposal

Go through the silent catches in `lib/features` and `lib/shared` and give each a category: harmless (`logIgnored`) or user-relevant (report, see the helper issue). Start with the Mongo database list.

Part of the error-handling epic.