fix(editor): real comment authors + overlay menu redesign

Comments showed the author's SLUG — which doubles as their personal scope
— instead of their name, because WasmTool passed presenceUser().id where
.name already existed.

- denormalize authorName/authorEmail onto each comment message + thread at
  write time, so a comment still reads correctly when its author is
  offline, renamed, or gone. `author` stays the SLUG: colorFor() and the
  "is this mine?" ownership checks compare it. Legacy comments fall back.
- session-identity keeps the email it was already fetching and discarding.

Overlay menu: restyle + reorganise into labelled sections (People /
Document / Comments / View) over one shared row shape, so sections can't
drift apart again.

- comments: four bare icons -> labelled rows (Add comment / Show list with
  count / Hide pins). The nested expand toggle is gone: the section IS the
  group, so it was a collapsible inside a collapsible.
- presence: facepile of initials -> one row per person with an explicit
  Follow/Stop. The separate "Following X" banner is deleted; that state now
  lives on the person's own row, so there is nothing to keep in sync.
- SourceChip gains a `muted` tone for known-dark surfaces; its solid
  variant is untouched for the light project pages that share it.

Fixes a regression the redesign introduced: the taller panel (z-50) covered
the comment popover (z-40), and since a popover can be opened FROM the
menu's thread list, the menu swallowed clicks on the popover it had just
spawned — delete was unreachable. Popover now z-[60].

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016p9kjdGBdcpwUSjJ3q5xg2

tests/web/comments-viewport-resize.spec.ts

@@ -29,10 +29,11 @@ async function bootAs(page: Page, user: string): Promise<void> {
       intervals: [1000],
     })
     .toMatch(TITLE);
-  await openOverlayMenu(page); // the comment bar lives in the overlay menu (0010)
-  await expect(page.getByTestId('comment-bar-toggle')).toBeVisible({ timeout: 30000 });
-  await page.getByTestId('comment-bar-toggle').click();
-  await expect(page.getByTestId('comment-mode-toggle')).toBeVisible();
+  // The comment controls live in the overlay menu's "Comments" section and are
+  // visible as soon as it opens — the nested expand toggle (comment-bar-toggle)
+  // is gone, since the section itself is the group.
+  await openOverlayMenu(page); // the comment controls live in the overlay menu (0010)
+  await expect(page.getByTestId('comment-mode-toggle')).toBeVisible({ timeout: 30000 });
 }
 
 /** Comments persist in the room's ydoc — start each run from a clean slate. */