feat(policies): backend-driven policy enforcement (frontend) (#6598)

## Summary
Adds the **Policies** feature (proprietary, behind the
`POLICIES_ENABLED` flag): backend-driven enforcement that runs a fixed
tool pipeline on documents, docked in the right tool sidebar alongside
Tools.

## Highlights
- **Policy catalog** — 5 categories; **Security** is wired (redact PII +
sanitize), the others are marked "Coming soon".
- **Backend as source of truth** — policies persist via the Policies
engine (`/api/v1/policies`), one policy per category, with a local cache
+ offline fallback.
- **Auto-run** — enabled policies run on every uploaded file: dispatch →
poll → import outputs into the workspace.
- **Security redact config** — PII preset dropdown + custom word/regex
entry + advanced options; tool params map to the backend endpoint
fields.
- **Activity feed** with retry on failures; **file badges** showing
which policies ran on a file (sidebar + files page), tinted to the
policy colour.
- Reuses the **Watched Folders** engine for each policy's backing
folder; policy-owned folders are filtered out of the Watched Folders UI.

## Notes
- Gated by `POLICIES_ENABLED` (true in proprietary, false in core) —
unreachable in the open-source build.
- Frontend-only diff; depends on the backend Policies engine and the
merged Watched Folders feature.

frontend/shared/components/ListRow.tsx

@@ -0,0 +1,79 @@
+import type { ReactNode } from "react";
+import "@shared/components/ListRow.css";
+import type { StatusTone } from "@shared/components/StatusBadge";
+
+export interface ListRowProps {
+  /** Leading visual (icon/avatar), shown in a tone-tinted square. */
+  leading?: ReactNode;
+  /** Tint for the leading square. Defaults to neutral. */
+  leadingTone?: StatusTone;
+  /** Primary line. */
+  title: ReactNode;
+  /** Secondary line. */
+  description?: ReactNode;
+  /** Tertiary line (e.g. timestamp). */
+  meta?: ReactNode;
+  /** Right-aligned content (badge, chevron, action). */
+  trailing?: ReactNode;
+  /** Makes the whole row a button. */
+  onClick?: () => void;
+  /** Draw a top hairline — set on every row after the first inside a list. */
+  divider?: boolean;
+  className?: string;
+}
+
+/**
+ * A single list row: a tone-tinted leading glyph + a title/description/meta
+ * stack + an optional trailing slot. Compose a divided list by wrapping rows in
+ * a {@code Card padding="none"} and setting {@code divider} on all but the first.
+ */
+export function ListRow({
+  leading,
+  leadingTone = "neutral",
+  title,
+  description,
+  meta,
+  trailing,
+  onClick,
+  divider,
+  className,
+}: ListRowProps) {
+  const classes = [
+    "sui-listrow",
+    divider ? "sui-listrow--divider" : "",
+    onClick ? "sui-listrow--interactive" : "",
+    className ?? "",
+  ]
+    .filter(Boolean)
+    .join(" ");
+
+  const content = (
+    <>
+      {leading && (
+        <span
+          className="sui-listrow__leading"
+          data-tone={leadingTone}
+          aria-hidden
+        >
+          {leading}
+        </span>
+      )}
+      <span className="sui-listrow__text">
+        <span className="sui-listrow__title">{title}</span>
+        {description && (
+          <span className="sui-listrow__desc">{description}</span>
+        )}
+        {meta && <span className="sui-listrow__meta">{meta}</span>}
+      </span>
+      {trailing && <span className="sui-listrow__trailing">{trailing}</span>}
+    </>
+  );
+
+  return onClick ? (
+    <button type="button" className={classes} onClick={onClick}>
+      {content}
+    </button>
+  ) : (
+    <div className={classes}>{content}</div>
+  );
+}