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.

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

@@ -0,0 +1,163 @@
+import { useEffect, useRef, useState } from 'react';
+import type { SearchAddon } from '@xterm/addon-search';
+import { ChevronDown, ChevronUp, X } from 'lucide-react';
+import { type TermTheme } from './theme';
+
+// ============================================================
+// SearchBar — kept from v1.10.4
+// ============================================================
+interface SearchBarProps {
+  searchRef: React.MutableRefObject<SearchAddon | null>;
+  theme: TermTheme;
+  onClose: () => void;
+}
+export function SearchBar({ searchRef, theme, onClose }: SearchBarProps) {
+  const [q, setQ] = useState('');
+  const [counts, setCounts] = useState<{ idx: number; total: number }>({ idx: -1, total: 0 });
+  const inputRef = useRef<HTMLInputElement | null>(null);
+  useEffect(() => {
+    inputRef.current?.focus();
+  }, []);
+  useEffect(() => {
+    const addon = searchRef.current;
+    if (!addon) return;
+    const sub = addon.onDidChangeResults(({ resultIndex, resultCount }) => {
+      setCounts({ idx: resultIndex, total: resultCount });
+    });
+    return () => sub.dispose();
+  }, [searchRef]);
+  useEffect(() => {
+    const addon = searchRef.current;
+    if (!addon) return;
+    if (q.length === 0) {
+      addon.clearDecorations?.();
+      setCounts({ idx: -1, total: 0 });
+      return;
+    }
+    addon.findNext(q, {
+      incremental: true,
+      decorations: {
+        matchBackground: theme.selectionBackground,
+        matchOverviewRuler: theme.cursor,
+        activeMatchBackground: theme.cursor,
+        activeMatchColorOverviewRuler: theme.cursor,
+      },
+    });
+  }, [q, searchRef, theme]);
+
+  function findNext(): void {
+    if (!q) return;
+    searchRef.current?.findNext(q);
+  }
+  function findPrev(): void {
+    if (!q) return;
+    searchRef.current?.findPrevious(q);
+  }
+  function onKey(ev: React.KeyboardEvent<HTMLInputElement>): void {
+    if (ev.key === 'Escape') {
+      ev.preventDefault();
+      onClose();
+      return;
+    }
+    if (ev.key === 'Enter') {
+      ev.preventDefault();
+      if (ev.shiftKey) findPrev();
+      else findNext();
+    }
+  }
+
+  return (
+    <div
+      style={{
+        position: 'absolute',
+        top: 8,
+        right: 8,
+        background: '#1a1d24',
+        border: '1px solid #2a2d34',
+        borderRadius: 8,
+        padding: 4,
+        display: 'flex',
+        alignItems: 'center',
+        gap: 4,
+        boxShadow: '0 4px 12px rgba(0,0,0,0.4)',
+        zIndex: 40,
+      }}
+    >
+      <input
+        ref={inputRef}
+        value={q}
+        onChange={(ev) => setQ(ev.target.value)}
+        onKeyDown={onKey}
+        placeholder="Search…"
+        style={{
+          background: 'transparent',
+          border: 0,
+          outline: 'none',
+          color: '#d6deeb',
+          padding: '8px 8px',
+          fontSize: 13,
+          width: 160,
+          minHeight: 36,
+        }}
+      />
+      {q.length > 0 && (
+        <span
+          style={{
+            fontSize: 11,
+            color: counts.total === 0 ? '#ef5350' : '#575656',
+            minWidth: 56,
+            textAlign: 'right',
+            padding: '0 4px',
+            whiteSpace: 'nowrap',
+          }}
+        >
+          {counts.total === 0
+            ? 'No match'
+            : counts.idx === -1
+              ? `${counts.total}+`
+              : `${counts.idx + 1} of ${counts.total}`}
+        </span>
+      )}
+      <button
+        type="button"
+        onClick={findPrev}
+        aria-label="Previous match"
+        title="Previous (Shift+Enter)"
+        style={iconBtnStyle}
+      >
+        <ChevronUp size={16} />
+      </button>
+      <button
+        type="button"
+        onClick={findNext}
+        aria-label="Next match"
+        title="Next (Enter)"
+        style={iconBtnStyle}
+      >
+        <ChevronDown size={16} />
+      </button>
+      <button
+        type="button"
+        onClick={onClose}
+        aria-label="Close search"
+        title="Close (Esc)"
+        style={iconBtnStyle}
+      >
+        <X size={16} />
+      </button>
+    </div>
+  );
+}
+
+const iconBtnStyle: React.CSSProperties = {
+  display: 'inline-flex',
+  alignItems: 'center',
+  justifyContent: 'center',
+  width: 44,
+  height: 44,
+  background: 'transparent',
+  border: 0,
+  color: '#d6deeb',
+  cursor: 'pointer',
+  borderRadius: 6,
+};