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/logFilters.ts

@@ -5,8 +5,11 @@
  */
 
 import type { Schema } from '@/types/schema';
+import type { ClientOnlyFilterEnum } from './schemaDeviationTypes';
 
 /**
+ * SCHEMA-DEVIATION: log-client-filters (see SCHEMA_DEVIATIONS.md)
+ *
  * The Stalwart JMAP backend rejects `level`/`event` as filter conditions on
  * `x:Log/query` (`unsupportedFilter`), even though both properties are
  * already returned per row. Until the backend adds real support, these two
@@ -18,17 +21,28 @@ export function withClientLogFilters(schema: Schema): Schema {
   const logList = schema.lists['x:Log'];
   if (!logList || !schema.enums['TracingLevel'] || !schema.enums['EventType']) return schema;
 
+  const levelFilter: ClientOnlyFilterEnum = {
+    type: 'enum',
+    field: 'level',
+    enumName: 'TracingLevel',
+    label: 'Level',
+    clientOnly: true,
+  };
+  const eventFilter: ClientOnlyFilterEnum = {
+    type: 'enum',
+    field: 'event',
+    enumName: 'EventType',
+    label: 'Event',
+    clientOnly: true,
+  };
+
   return {
     ...schema,
     lists: {
       ...schema.lists,
       'x:Log': {
         ...logList,
-        filters: [
-          ...(logList.filters ?? []),
-          { type: 'enum', field: 'level', enumName: 'TracingLevel', label: 'Level', clientOnly: true },
-          { type: 'enum', field: 'event', enumName: 'EventType', label: 'Event', clientOnly: true },
-        ],
+        filters: [...(logList.filters ?? []), levelFilter, eventFilter],
       },
     },
   };