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.stories.tsx

@@ -0,0 +1,80 @@
+import type { Meta, StoryObj } from "@storybook/react-vite";
+import { ListRow } from "@shared/components/ListRow";
+import { Card } from "@shared/components/Card";
+import { StatusBadge } from "@shared/components/StatusBadge";
+
+const meta: Meta<typeof ListRow> = {
+  title: "Primitives/ListRow",
+  component: ListRow,
+  tags: ["autodocs"],
+  parameters: { layout: "padded" },
+  decorators: [
+    (S) => (
+      <div style={{ maxWidth: "24rem" }}>
+        <S />
+      </div>
+    ),
+  ],
+};
+export default meta;
+type Story = StoryObj<typeof ListRow>;
+
+function Dot({ ch }: { ch: string }) {
+  return <span style={{ fontSize: 12, fontWeight: 700 }}>{ch}</span>;
+}
+
+export const Default: Story = {
+  args: {
+    leading: <Dot ch="✓" />,
+    leadingTone: "success",
+    title: "MSA_Acme_2026.pdf",
+    description: "Classified as Contract • 3 tables extracted",
+    meta: "2h ago",
+  },
+};
+
+/** A divided list inside a padding-none Card — the canonical usage. */
+export const InCard: Story = {
+  render: () => (
+    <Card padding="none">
+      <ListRow
+        leading={<Dot ch="✓" />}
+        leadingTone="success"
+        title="MSA_Acme_2026.pdf"
+        description="Classified as Contract • 3 tables extracted"
+        meta="2h ago"
+      />
+      <ListRow
+        divider
+        leading={<Dot ch="!" />}
+        leadingTone="warning"
+        title="scan_002.pdf"
+        description="Low confidence (62%) • flagged for review"
+        meta="Yesterday"
+        trailing={
+          <StatusBadge tone="warning" size="sm">
+            Flagged
+          </StatusBadge>
+        }
+      />
+      <ListRow
+        divider
+        leading={<Dot ch="✓" />}
+        leadingTone="success"
+        title="Invoice_4471.pdf"
+        description="Classified as Invoice • renamed to standard"
+        meta="5h ago"
+      />
+    </Card>
+  ),
+};
+
+export const Interactive: Story = {
+  args: {
+    leading: <Dot ch="→" />,
+    leadingTone: "info",
+    title: "Clickable row",
+    description: "The whole row is a button",
+    onClick: () => {},
+  },
+};