refactor(events): scope queryHistoryDidUpdate and linkedSQLFoldersDidUpdate by connection id

[datlechin]

Summary

Two more Void-payload AppEvents subjects with per-connection subscribers gain a UUID? payload, matching the pattern from PRs #1159 and #1160.

queryHistoryDidUpdate

PassthroughSubject<Void, Never> -> PassthroughSubject<UUID?, Never>.

• QueryHistoryManager.addHistory(...) sends entry.connectionId (history entries always carry a non-nil connectionId).
• deleteHistory(id:) and clearAllHistory() send nil (the connection isn't easily recoverable from the id-only delete API; clearAllHistory legitimately spans all connections).
• HistoryPanelView is per-connection and now skips events that don't match its connectionId.

Previously, executing a query on connection A reloaded every other open window's history panel.

linkedSQLFoldersDidUpdate

PassthroughSubject<Void, Never> -> PassthroughSubject<UUID?, Never>.

• SQLFolderWatcher.scheduleFullRescan(...) and scheduleDebouncedRescan() rescan across all enabled folders, so they always send nil. The shape change is forward-looking so any future per-folder rescan path can carry the affected connection id without re-shaping the bus.
• Subscribers ConnectionDataCache, MainContentCoordinator.checkOpenTabsForExternalModification, and SQLEditorView now apply payload == nil || payload == self.connectionId. Today every event still carries nil so the filter is a no-op for the rescan path; once any sender starts emitting a specific id (e.g. a future per-folder reload), per-connection subscribers will short-circuit unrelated events automatically.

Why this matters

Audit X-shape pattern, continuing the work in PRs #1148, #1159, #1160. After this PR the only remaining Void-payload subjects on AppEvents are genuinely global (themeChanged, accessibilityTextSizeChanged, editorSettingsChanged, dataGridSettingsChanged, aiSettingsChanged, terminalSettingsChanged, licenseStatusDidChange, syncChangeTracked, mcpAuditLogChanged, pluginsRejected, linkedFoldersDidUpdate, mainWindowWillClose).

Test plan

• Open two windows on two different connections. Run a query on connection A and confirm only connection A's history panel reloads.
• Delete a history entry; both panels reload (since the sender passes nil).
• Clear all history; both panels reload.
• Modify a linked SQL file on disk; confirm watcher fires and the open windows' caches refresh.
• swiftlint --strict clean.