bug(connections): PG schema tree must not show stale objects with error

[ZhuchkaTriplesix]

Parent

Part of #463

Severity

Medium

Problem

After a failed reload in _PgSchemaNodeState._loadObjects, state sets _error but leaves _loaded true and keeps prior _tables / _views lists. Build shows the error block and paints old object groups — a broken refresh looks like current schema data.

Evidence

• lib/features/connections/connections_panel_pg_tree.dart (~684–776)
• Bugbot review dev vs main (2026-07-27)

Acceptance

• On load failure, either clear object lists or hide them while _error != null
• Retry reloads cleanly
• Successful reload still shows objects

Suggested fix

On catch: set _error, _loading = false, and clear lists / set _loaded = false; or in build, skip object groups when _error != null.

[ZhuchkaTriplesix]

Fixed in #469 (merged to dev).