fix(schema): track client-side schema deviations, restore schema.ts fidelity

src/types/schema.ts had drifted from the official schema contract: a
`clientOnly` field had been added to `FilterEnum` to support client-side
log filtering. Restored it to match upstream exactly and moved the
deviation-only type into a new intersection type in
src/lib/schemaDeviationTypes.ts instead.

Audited the codebase for every place the UI does something the official
schema doesn't support and tagged each with `// SCHEMA-DEVIATION: <id>`,
documented in the new SCHEMA_DEVIATIONS.md registry (what, why, and the
ideal server-side fix):

- log-client-filters: Level/Event filters on Log Entries, applied
  client-side because x:Log/query rejects them as JMAP filters.
- account-quota-usage-column: synthetic quotaUsage column on the
  Accounts list.
- mailbox-client-hierarchy-sort: full-fetch + client-side sort to
  reconstruct mailbox parent/child hierarchy.
- webapp-enabled-column-fallback: synthetic "Enabled" column label for
  x:Application when the schema list doesn't define one.

Other viewName/objectName special cases (x:OtpAuth, x:Expression,
x:Rate, x:Action, x:Trace, CustomComponent/*) were checked against
upstream and are pre-existing architecture, not fork deviations.

src/lib/schemaDeviationTypes.ts

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <hello@stalw.art>
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ */
+
+import type { FilterEnum } from '@/types/schema';
+
+/**
+ * Type augmentations for tracked schema deviations (see SCHEMA_DEVIATIONS.md).
+ *
+ * `src/types/schema.ts` mirrors the server's schema contract and must stay
+ * aligned with the official webui/server types — it is never edited to
+ * accommodate a deviation. When a deviation needs to carry extra data on an
+ * otherwise-official schema shape, the augmented type lives here instead,
+ * as an intersection with the official type, and is imported only by the
+ * deviation's own code.
+ */
+
+// SCHEMA-DEVIATION: log-client-filters (see SCHEMA_DEVIATIONS.md)
+export type ClientOnlyFilterEnum = FilterEnum & { clientOnly?: boolean };
+
+export function isClientOnlyFilterEnum(f: FilterEnum): f is ClientOnlyFilterEnum {
+  return (f as ClientOnlyFilterEnum).clientOnly === true;
+}