search: real autocomplete previews + clearer placeholder

PLACEHOLDER: "Search broadcast news…" → "Search articles, gear,
vendors". Drops the weird ellipsis and the "we're a broadcast site
so 'broadcast news' is redundant" feel.

API (/api/search/suggest):
- Match expanded from {title, author_name} to
  {title, excerpt, content, author_name} — surfaces hits when the
  phrase lives deep in the article body.
- Returns a snippet object {text, matchStart, matchEnd} sliced
  from the first hit (HTML-stripped), with ~80 chars of context on
  either side and "…" markers when truncated.
- Returns matched_in: 'title' | 'excerpt' | 'content' | 'author' so
  the UI can show "match in article body" / "match in byline".
- Returns date + author_name on each result.

UI dropdown (Header.tsx):
- Each suggestion now renders three rows:
  1) Title (bold) + category chip
  2) Snippet with the matched substring wrapped in <mark>
  3) Author byline + date + (if match wasn't in title) a tag
     showing where the match occurred
- Vertical stacking with a colored left-border on hover so the
  active suggestion is visible.

CSS:
- Stack item layout, snippet with -webkit-line-clamp:2 so long
  matches don't overflow.
- <mark> background uses the accent blue at 28% so the highlight
  reads against the dark card.

src/styles/tailwind.css

@@ -867,22 +867,31 @@ h1, h2, h3 {
 
 .bb-browse-search-suggest-item {
   display: flex;
-  align-items: center;
-  justify-content: space-between;
-  gap: 10px;
-  padding: 8px 14px;
+  flex-direction: column;
+  gap: 4px;
+  padding: 10px 14px;
   font-family: var(--font-body);
   font-size: 13px;
   color: #d1d8e4;
   text-decoration: none;
   transition: background var(--transition-fast), color var(--transition-fast);
+  border-left: 2px solid transparent;
 }
 
 .bb-browse-search-suggest-item:hover,
 .bb-browse-search-suggest-item:focus-visible {
-  background: rgba(59, 130, 246, 0.12);
+  background: rgba(59, 130, 246, 0.10);
   color: #ffffff;
   outline: none;
+  border-left-color: var(--color-accent);
+}
+
+.bb-browse-search-suggest-row1 {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 10px;
+  min-width: 0;
 }
 
 .bb-browse-search-suggest-title {
@@ -891,6 +900,8 @@ h1, h2, h3 {
   white-space: nowrap;
   overflow: hidden;
   text-overflow: ellipsis;
+  font-weight: 600;
+  color: #e6ecf3;
 }
 
 .bb-browse-search-suggest-cat {
@@ -904,6 +915,52 @@ h1, h2, h3 {
   opacity: 0.75;
 }
 
+.bb-browse-search-suggest-snippet {
+  font-size: 12px;
+  color: #98a3b3;
+  line-height: 1.4;
+  display: -webkit-box;
+  -webkit-line-clamp: 2;
+  -webkit-box-orient: vertical;
+  overflow: hidden;
+}
+
+.bb-browse-search-suggest-mark {
+  background: rgba(59, 130, 246, 0.28);
+  color: #ffffff;
+  padding: 0 2px;
+  border-radius: 2px;
+  font-weight: 600;
+}
+
+.bb-browse-search-suggest-meta {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 6px;
+  font-size: 11px;
+  color: #6b7585;
+  font-family: var(--font-mono);
+  letter-spacing: 0.02em;
+}
+
+.bb-browse-search-suggest-meta .bb-dot {
+  opacity: 0.5;
+}
+
+.bb-browse-search-suggest-mark-tag {
+  display: inline-block;
+  margin-left: 4px;
+  padding: 1px 6px;
+  background: rgba(59, 130, 246, 0.10);
+  color: var(--color-accent);
+  font-size: 9px;
+  font-weight: 700;
+  letter-spacing: 0.12em;
+  text-transform: uppercase;
+  border-radius: 2px;
+}
+
 .bb-browse-search-suggest-all {
   border-top: 1px solid #1f2937;
   margin-top: 2px;