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-workspace/tests/workspace-browser.spec.tsx

@@ -406,13 +406,13 @@ describe('WorkspaceBrowser', () => {
     const input = screen.getByLabelText<HTMLInputElement>('Workspace name')
     expect(input.value).toBe('Alpha')
     // Unchanged and blank names stay blocked.
-    expect((screen.getByRole('button', { name: 'Rename' })).disabled).toBe(true)
+    expect(screen.getByRole<HTMLButtonElement>('button', { name: 'Rename' }).disabled).toBe(true)
     fireEvent.change(input, { target: { value: '   ' } })
-    expect((screen.getByRole('button', { name: 'Rename' })).disabled).toBe(true)
+    expect(screen.getByRole<HTMLButtonElement>('button', { name: 'Rename' }).disabled).toBe(true)
     // A duplicate of another workspace's title shows the inline conflict.
     fireEvent.change(input, { target: { value: ' Beta ' } })
     expect(screen.getByRole('alert').textContent).toBe('A workspace named “Beta” already exists.')
-    expect((screen.getByRole('button', { name: 'Rename' })).disabled).toBe(true)
+    expect(screen.getByRole<HTMLButtonElement>('button', { name: 'Rename' }).disabled).toBe(true)
     fireEvent.change(input, { target: { value: 'Gamma' } })
     fireEvent.click(screen.getByRole('button', { name: 'Rename' }))
     expect(renameWorkspace).toHaveBeenCalledWith(wid('alpha'), 'Gamma')
@@ -475,13 +475,13 @@ describe('WorkspaceBrowser', () => {
     expect(dialog.textContent).toContain('folder and session logs will be kept')
     expect(dialog.textContent).toContain('sessions will appear under Ungrouped')
 
-    const confirm = screen.getByRole('button', { name: 'Delete workspace' })
+    const confirm = screen.getByRole<HTMLButtonElement>('button', { name: 'Delete workspace' })
     fireEvent.click(confirm)
     fireEvent.click(confirm)
     expect(deleteWorkspace).toHaveBeenCalledOnce()
     expect(deleteWorkspace).toHaveBeenCalledWith(wid('alpha'))
     expect(confirm.disabled).toBe(true)
-    expect((screen.getByRole('button', { name: 'Cancel' })).disabled).toBe(true)
+    expect(screen.getByRole<HTMLButtonElement>('button', { name: 'Cancel' }).disabled).toBe(true)
     expect(screen.getByRole('status').textContent).toBe('Deleting workspace…')
     fireEvent.keyDown(document, { key: 'Escape' })
     fireEvent.click(screen.getByRole('button', { name: 'Close' }))