feat(ui): inline expansion for mobile stream entries

Replace bottom-sheet peek with inline accordion at ≤900px.
Entries expand in-place with grid-template-rows animation (0.2s).
Body clamped to 3 lines; fullscreen uncaps it.
Selection toggles DOM classes instead of re-rendering for fluid j/k nav.

web/style.css

@@ -375,28 +375,72 @@ main.focus-peek .resize-handle { visibility: hidden; }
 }
 
 .entity-item {
+    cursor: pointer;
+    border-left: 2px solid transparent;
+    transition: background var(--t-fast), border-left-color var(--t-fast);
+}
+
+.entity-head {
     display: flex;
     align-items: center;
     gap: 8px;
     padding: 5px 16px 5px 20px;
-    cursor: pointer;
-    border-left: 2px solid transparent;
     min-height: 32px;
-    transition: background var(--t-fast), border-left-color var(--t-fast);
 }
 
 .entity-item:hover { background: var(--surf); }
 .entity-item.selected { background: var(--surf); border-left-color: var(--accent); }
 
+.entity-exp { display: none; }
+
+.entity-exp-clip { overflow: hidden; }
+
+.exp-inner {
+    padding: .6rem 1rem .7rem calc(20px + 14px + 8px);
+    border-top: 1px solid var(--border);
+}
+
+.exp-body {
+    font-family: var(--mono);
+    font-size: 11px;
+    color: var(--text);
+    line-height: 1.7;
+    white-space: pre-wrap;
+    word-break: break-word;
+    margin-bottom: .5rem;
+    display: -webkit-box;
+    -webkit-line-clamp: 3;
+    -webkit-box-orient: vertical;
+    overflow: hidden;
+}
+
+.entity-item.exp-full .exp-body {
+    -webkit-line-clamp: unset;
+    overflow: visible;
+}
+
+.exp-tags { display: flex; flex-wrap: wrap; gap: 4px; margin-bottom: .5rem; }
+
+.exp-acts { display: flex; flex-wrap: wrap; gap: 4px; }
+
+.exp-toolbar {
+    display: none;
+    justify-content: space-between;
+    margin-top: .5rem;
+    padding-top: .5rem;
+    border-top: 1px solid var(--border);
+}
+
 .entity-item.is-card {
     background: var(--surf);
     margin: 2px 10px;
     border-radius: var(--r2);
     border: 1px solid var(--border);
     border-left-width: 1px;
-    padding: 7px 12px;
 }
 
+.entity-item.is-card .entity-head { padding: 7px 12px; }
+
 .entity-item.is-card:hover { border-color: var(--muted); }
 .entity-item.is-card.selected { border-color: var(--accent); background: var(--a-bg); }
 
@@ -785,13 +829,6 @@ main.focus-peek .resize-handle { visibility: hidden; }
     overflow: hidden;
 }
 
-.peek-mobile-bar {
-    display: none;
-    justify-content: space-between;
-    padding: 6px 12px;
-    border-bottom: 1px solid var(--border);
-}
-
 .peek-mobile-btn {
     font-family: var(--mono);
     font-size: 14px;
@@ -1488,8 +1525,23 @@ kbd { background: var(--raised); border: 1px solid var(--border); border-radius:
         transition: transform var(--t-base);
         z-index: 50;
     }
-    #detail-pane.visible { transform: translateY(0); }
-    #detail-pane.peek-full { height: 100vh; height: 100dvh; top: 0; }
-    .peek-mobile-bar { display: flex; }
+    #detail-pane { display: none !important; }
+    .entity-exp {
+        display: grid;
+        grid-template-rows: 0fr;
+        transition: grid-template-rows .2s ease;
+    }
+    .entity-item.selected .entity-exp { grid-template-rows: 1fr; }
+    .entity-item.selected .exp-toolbar { display: flex; }
+    .entity-item.exp-full {
+        position: fixed;
+        inset: 0;
+        z-index: 60;
+        background: var(--bg);
+        overflow-y: auto;
+        border-left: none;
+    }
+    .entity-item.exp-full .entity-exp { grid-template-rows: 1fr; }
+    .entity-item.exp-full .exp-inner { padding-top: 1rem; padding-bottom: 2rem; }
     main.focus-peek #entity-panel { display: block; overflow: auto; min-width: 0; }
 }