refactor: codebase audit cleanup — dead code, dedup, module splits

Multi-agent audit + aggressive cleanup across server/web/coder/booterm,
delivered behind a DEFER discipline so none of the in-flight files were
touched. Removes dead code/deps/columns, dedups server + coder helpers,
and splits the oversized modules (tools.ts, opencode-server.ts,
sentinel-summaries, turn.ts, TerminalPane.tsx) behind stable contracts.
Adds 78 parity/unit tests (server 587, coder 323); fixes two latent bugs
(ChatPane queue keys, FileViewerOverlay blank-line parity).

Intended tag: v2.7.12-audit-cleanup.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/components/panes/terminal/TerminalHotkeyBar.tsx

@@ -0,0 +1,115 @@
+import { useCallback } from 'react';
+import { Maximize2 } from 'lucide-react';
+import { cn } from '@/lib/utils';
+
+// ============================================================
+// TerminalHotkeyBar — v1.10.8d port of boolab's TerminalHotkeyBar.jsx +
+// terminalHotkeysStore.js DEFAULT_BAR. The catalog is hardcoded inline (no
+// zustand store, no settings UI) — single-user homelab doesn't need either.
+// Add new entries by extending HOTKEY_BAR below.
+// ============================================================
+type Hotkey =
+  | { id: string; label: string; bytes: string; sticky?: undefined }
+  | { id: string; label: string; sticky: 'ctrl'; bytes?: undefined };
+
+const HOTKEY_BAR: Hotkey[] = [
+  { id: 'esc', label: 'Esc', bytes: '\x1b' },
+  { id: 'shift-tab', label: '⇧Tab', bytes: '\x1b[Z' },
+  { id: 'tab', label: 'Tab', bytes: '\t' },
+  { id: 'ctrl', label: 'Ctrl', sticky: 'ctrl' },
+  { id: 'ctrl-c', label: 'Ctrl+C', bytes: '\x03' },
+  { id: 'arrow-up', label: '↑', bytes: '\x1b[A' },
+  { id: 'arrow-down', label: '↓', bytes: '\x1b[B' },
+  { id: 'arrow-left', label: '←', bytes: '\x1b[D' },
+  { id: 'arrow-right', label: '→', bytes: '\x1b[C' },
+];
+
+interface TerminalHotkeyBarProps {
+  ctrlArmed: boolean;
+  onSendBytes: (bytes: string) => void;
+  onArmCtrl: () => void;
+  onFit: () => void;
+}
+
+export function TerminalHotkeyBar({
+  ctrlArmed,
+  onSendBytes,
+  onArmCtrl,
+  onFit,
+}: TerminalHotkeyBarProps) {
+  // Stop the touch from reaching the terminal pane below (which calls
+  // preventDefault on touchmove to suppress page-scroll). Without this a
+  // tap-and-drag on a hotkey button would also scroll the terminal buffer.
+  const stopTouch = useCallback((e: React.TouchEvent) => e.stopPropagation(), []);
+  const press = useCallback(
+    (entry: Hotkey) => {
+      if (entry.sticky === 'ctrl') {
+        onArmCtrl();
+      } else if (entry.bytes !== undefined) {
+        onSendBytes(entry.bytes);
+      }
+    },
+    [onArmCtrl, onSendBytes],
+  );
+
+  return (
+    <div
+      role="toolbar"
+      aria-label="Terminal hotkeys"
+      className="flex shrink-0 items-center gap-1 overflow-x-auto border-b border-border bg-muted/30 px-2 py-1"
+      style={{
+        scrollbarWidth: 'thin',
+        WebkitOverflowScrolling: 'touch',
+        // Suppress iOS native swipe-back gesture starting on the bar; pinch
+        // and other multi-touch gestures still pass through.
+        touchAction: 'pan-x',
+      }}
+      onTouchStart={stopTouch}
+      onTouchMove={stopTouch}
+    >
+      {HOTKEY_BAR.map((entry) => {
+        const isCtrl = entry.sticky === 'ctrl';
+        const armed = isCtrl && ctrlArmed;
+        return (
+          <button
+            key={entry.id}
+            type="button"
+            onClick={() => press(entry)}
+            aria-pressed={isCtrl ? armed : undefined}
+            aria-label={entry.label}
+            className={cn(
+              'shrink-0 rounded border px-2 py-0.5 text-xs font-mono transition-colors',
+              armed
+                ? 'border-primary bg-primary text-primary-foreground'
+                : 'border-border text-foreground hover:bg-muted',
+            )}
+            style={{
+              minHeight: 28,
+              minWidth: 36,
+              WebkitTouchCallout: 'none',
+              userSelect: 'none',
+            }}
+          >
+            {entry.label}
+          </button>
+        );
+      })}
+      <button
+        type="button"
+        onClick={onFit}
+        aria-label="Fit terminal"
+        title="Fit terminal to container"
+        className="shrink-0 inline-flex items-center justify-center rounded border border-border text-foreground hover:bg-muted"
+        style={{
+          minHeight: 28,
+          minWidth: 36,
+          paddingInline: 8,
+          WebkitTouchCallout: 'none',
+          userSelect: 'none',
+        }}
+      >
+        <Maximize2 size={14} />
+      </button>
+    </div>
+  );
+}