chore(lint): clear the semantic .tsx backlog

Hand fixes for the findings --fix cannot touch, mirroring the fixes
already applied on the fe-docs feature branch (same file, same shape)
so its eventual rebase resolves cleanly:

- restore the return the no-confusing-void-expression autofix ate in
  useAbsentSnapshot (typed S | undefined; hook call kept for hook-order
  stability, undefined returned explicitly);
- re-type DOM queries the no-unnecessary-type-assertion autofix broke:
  getByRole<HTMLButtonElement>(...) generics instead of the removed
  as-casts (the eslint program and the client tsconfig aggregate
  disagree about these casts; the generic form satisfies both);
- justified eslint-disable for the deliberate legacy paths: keyCode 229
  IME-composition detection, execCommand clipboard fallbacks, lib.dom
  clipboard optionality, and the any-typed Reflect.get/this probes in
  test fakes;
- drop the dead react/no-danger directive (eslint-plugin-react is not
  loaded, so the rule never applied) keeping its shiki rationale;
- delete the tautological 'Z' comparison and the renameTarget null
  check already implied by renameBlocked;
- css-module non-null assertions replaced by type widening
  (Button className, TAG_CLASS Record) per the established pattern;
- misc: max-len comment wraps, void generic drop in the deferred test
  helper, unused type imports, floating selectWorkspace promises voided,
  member-delimiter newlines in inline type literals.

packages/client/ui-trajectory/src/client/TrajectoryCell.tsx

@@ -16,11 +16,11 @@ const KIND_LABEL: Record<TrajectoryCellKind, string> = {
   subtool: 'Sub',
 }
 
-const TAG_CLASS: Record<TrajectoryCellKind, string> = {
-  user: css.tagUser!,
-  message: css.tagMessage!,
-  tool: css.tagTool!,
-  subtool: css.tagSubtool!,
+const TAG_CLASS: Record<TrajectoryCellKind, string | undefined> = {
+  user: css.tagUser,
+  message: css.tagMessage,
+  tool: css.tagTool,
+  subtool: css.tagSubtool,
 }
 
 export interface TrajectoryCellProps extends HTMLAttributes<HTMLDivElement> {
@@ -84,7 +84,7 @@ export function TrajectoryCell({
     <div className={rootClass} data-kind={kind} data-selected={selected || undefined} {...rest}>
       <span className={css.index}>#{index}</span>
       <span className={css.tagSlot}>
-        <span className={`${css.tag} ${TAG_CLASS[kind]}`}>{KIND_LABEL[kind]}</span>
+        <span className={[css.tag, TAG_CLASS[kind]].filter((c): c is string => c !== undefined).join(' ')}>{KIND_LABEL[kind]}</span>
       </span>
       <span className={css.text}>{text}</span>
       <span className={css.trailing}>