refactor: remove dead code and consolidate SQL escaping

[datlechin]

What

Two small, verified cleanups from a read-only codebase audit. No behavior change for users.

Dead code removal

Each symbol was confirmed to have zero references repo-wide (whole-word grep across app, plugins, and test targets) before removal:

• TokenPermissionFilter (whole file) and its ConnectionIdentifiable protocol, both never used.
• ConnectionEnvironment enum (badge type) never instantiated.
• IdentifiableURL / IdentifiableConnections sheet-binding wrappers, never bound.
• SQLFunctionLiteral marker struct, superseded by the isSQLFunctionExpression string check.
• MCPAuditLogStorage.TimeRange nested enum, never produced or consumed.

SQL escaping consolidation

DatabaseDriver's default quoteIdentifier and escapeStringLiteral duplicated the canonical SQLEscaping logic verbatim. They now delegate to SQLEscaping, and a new SQLEscaping.quoteIdentifier replaces an inline copy in QueryResultExportDataSource. The export fallback now also strips null bytes, matching the canonical ANSI rule. Added quoteIdentifier unit tests.

Verification

• Every deleted symbol grep-confirmed unreferenced (including test targets).
• swiftlint lint --strict clean on all changed files.
• Build is for the reviewer to run.

Deliberately out of scope

• 19 String(localized:) interpolation fixes in plugins (real, but behavior-neutral and touch separately-released bundles, better as a plugin PR).
• The no-comments rule (~1,617 lines across 219 files): too large and judgment-heavy for a blanket pass.
• 3 unused LSP/Copilot wire types: verifiably unused now but likely scaffolding for in-progress work, left in place.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Publish the debounced ranking result

In SuggestionViewModel.cursorsUpdated, the window only replaces items with the value returned synchronously from completionOnCursorMove; nothing observes this cache. When the user types a prefix and then pauses or accepts with Tab, the debounced filterAndRank result stored here is never shown for that final prefix, so the visible list keeps the immediate filterByPrefix ordering and stale/no match ranges instead of the ranked result this task computed.

Useful? React with 👍 / 👎.

[chatgpt-codex-connector]

Keep refilter work cancellable

When typing just slowly enough for the 30 ms debounce to elapse, canceling cursorRefilterTask on the next cursor move does not cancel the unstructured Task.detached spawned here. Stale filterAndRank calls can continue over the full suggestion list while newer prefixes start their own work, so CPU-heavy refilters pile up in the large-list fast-typing case this change is meant to fix; keep the ranking in the cancellable task or retain and cancel the detached handle.

Useful? React with 👍 / 👎.