refactor(ui): give the icons one vocabulary and sweep the call sites

`plus` meant "add to the queue", "add to a playlist", "make a new
playlist" and "you do not own this" -- the first two adjacent in the
same context menu, so two neighbouring items were the same glyph doing
different things. `list` meant the queue (the button that opens it), the
Playlists destination, and adding to the queue in `queue-panel` alone.
Two icons carrying seven meanings is not a vocabulary, and nothing
catches it: a wrong-but-real icon renders perfectly.

`utils/icon-language.ts` is the table, beside `library-status.ts` as the
issue suggested. The rule it is built on is that an icon names the
**noun** it acts on, not the verb: "add to queue" and "add to playlist"
are one verb on two nouns, so the noun is what differs -- which is why
adding to a playlist wears the Playlists destination's own icon, and why
the queue took `bars-staggered` and stopped wearing Playlists'. `plus`
keeps the one meaning it is unambiguous about, making something that is
not there yet, which covers New Playlist and the drop zones.

`bars-staggered` is the only new glyph, vendored through names.txt and
fetch-icons.mjs after confirming it is in Font Awesome **Free** 7.3.1.

Two things this found rather than changed:

- The request toggle's outline/solid pair was already in the app and
  already right -- `explore-album-details`'s "Request this" button has
  used `regular/bookmark` -> `solid/bookmark` since it was written --
  while the badge forty pixels away showed a **plus** for the same
  state. That is `utils/library-status.ts`'s fault one layer down: it
  made the two surfaces agree on what wanting *means* and left them
  disagreeing on what it looks like.
- `explore-artist-details`'s Follow button was `bookmark-check`, which
  is Font Awesome **Pro** and has never been bundled, so it has drawn
  the missing-icon fallback -- a circled question mark -- for every
  followed artist since it was written. `requested-badge.spec.ts` was
  written for exactly this bug on the album button and says so in its
  docstring; this is the same bug one component over, still live,
  because `offline-icons.spec.ts` sweeps `__yjIconMisses` and no spec
  had ever followed an artist.

So the test does what reaching the state cannot. `icon-language.test.ts`
reads every `src/**/*.ts` as raw text and fails on a governed name
written outside the table, and separately asserts every `ICON_*` is a
*bundled* name -- which is what makes a Pro name a failing test rather
than a runtime report from a state something has to reach first. Its
first assertion is that it read any source at all, because a sweep over
an empty glob passes.

`chrome.test.ts` asserted `['check', 'bookmark', 'plus']` and so pinned
the badge's glyphs against the vocabulary they were meant to follow; it
names them from the table now, and keeps the assertion that the three
differ, which is the property the states actually need.

Downloads keeps the solid bookmark on purpose. That is one word twice,
not two words: the badge says the entity is on your list and the nav
item is that list.

Closes #34

CLAUDE.md

@@ -1448,6 +1448,52 @@ is therefore **reported at runtime** to `window.__yjIconMisses` and
 drawn as a fallback — an e2e sweep asserts there are none — since a
 missing icon used to be impossible, the CDN having had everything.
 
+**What each icon *means* is a second table, and it is
+`utils/icon-language.ts`.** Bundling answers "does this name resolve";
+nothing answered "does this name mean what the one next to it means",
+and a wrong-but-real icon renders perfectly. So `plus` came to mean add
+to the queue, add to a playlist, make a new playlist **and** you do not
+own this — the first two *adjacent in the same context menu* — while
+`list` meant the queue, the Playlists destination and adding to the
+queue.
+
+The rule the table is built on: **an icon names the noun it acts on,
+not the verb.** "Add to queue" and "add to playlist" are one verb on
+two nouns, so the noun is what has to differ — which is why adding to a
+playlist wears the Playlists destination's own icon, and why the queue
+got `bars-staggered` and stopped wearing Playlists'. `plus` keeps the
+one meaning it is unambiguous about, making something that is not there
+yet.
+
+Four things about it are load-bearing:
+
+- **The request toggle is one glyph in two weights**
+  (`regular/bookmark` → `solid/bookmark`), because two states of a
+  toggle have to read as each other's opposite and a plus against a
+  bookmark does not. The pair was *already in the app and already
+  right* on `explore-album-details`'s "Request this" button while the
+  badge forty pixels away showed a plus — `utils/library-status.ts`'s
+  fault one layer down, having made the two agree on what wanting means
+  and left them disagreeing on what it looks like.
+- **Downloads keeps the solid bookmark, deliberately.** That is the
+  same word twice, not two words: the badge says "this is on your
+  list" and the nav item is that list.
+- **`icon-language.test.ts` sweeps the source**, because the rule is
+  about every call site and checking one checks nothing — the same
+  shape as `TestNoDirectRuntimeEmits`. It reads every `src/**/*.ts` as
+  raw text and fails on a literal `name="plus"` or `icon: 'list'`
+  outside the table, and its **first assertion is that it read
+  anything at all**, since a sweep over an empty glob passes.
+- **It also asserts every `ICON_*` is bundled**, which closes the loop
+  the runtime cannot: `bookmark-check` is Font Awesome **Pro** and sat
+  on `explore-artist-details`'s Follow button, drawn for every followed
+  artist as a circled question mark. `offline-icons.spec.ts` sweeps
+  `__yjIconMisses` and could not see it, because no spec had ever
+  followed an artist — the same fault `requested-badge.spec.ts` was
+  written for, one component over, still live. A name computed from
+  state was only checkable from the state; now it is checkable from the
+  table.
+
 **An album page says how much of the album is yours.**
 `explore-album-details` is a *catalog* page and there is no
 library-side album detail page at all, so the album on it may be