feat(dsh-plugin-browserskill): add the web client half with a browser_screenshot toolview

Make the package dual-face: a dsh.client declaration (platform 'web')
plus an exports["./client"] bundle built in dsh's closure-factory shape
(window.__ModuleLoader__.load handoff, platform modules external,
everything else inlined, CSS Modules via lightningcss).

The client registers a keyed 'tool.call.toolview' view for
browser_screenshot that keeps the terminal block (command + output) and,
when the settled result carries an image block, resolves the durable
attachment through the client session's authorized readAttachment RPC
and renders it with the shared MessageImage thumbnail/lightbox atoms.
Path-only results render unchanged; every other browser_* tool keeps
the stock terminal card.

Tests: view-model derivation (running/ok/error, image vs path-only),
component rendering through @testing-library/react + happy-dom, and the
registration key. biome.json now excludes the package's lib/ build
output (same treatment as dist/).

packages/dsh-plugin-browserskill/src/client/ScreenshotToolView.module.css

@@ -0,0 +1,57 @@
+/* browser_screenshot toolview: disclosure row over a terminal block plus the
+   screenshot image. Semantic tokens only (--dsw-alias-*), no literal colors. */
+
+.card {
+  display: flex;
+  flex-direction: column;
+}
+
+.summary {
+  min-width: 0;
+  margin-left: 6px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  color: var(--dsw-alias-label-secondary);
+}
+
+.card[data-state="error"] .summary {
+  color: var(--dsw-alias-label-error);
+}
+
+.body {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  padding: 4px 0 4px 22px;
+}
+
+.image-wrap {
+  display: flex;
+}
+
+.inspect-button {
+  align-self: flex-start;
+  border: none;
+  background: none;
+  padding: 0;
+  font: inherit;
+  font-size: 12px;
+  color: var(--dsw-alias-label-tertiary);
+  cursor: pointer;
+}
+
+.inspect-button:hover {
+  color: var(--dsw-alias-label-secondary);
+}
+
+.inspect-button:focus-visible {
+  outline: 2px solid var(--dsw-alias-border-focus);
+  outline-offset: 2px;
+  border-radius: 2px;
+}
+@media (prefers-reduced-motion: reduce) {
+  .inspect-button {
+    transition: none;
+  }
+}