feat(05-03): PolicyList, PolicyFormModal, IncidentList and costs tab navigation

- Create PolicyList with utilization bars, edit/delete, empty state
- Create PolicyFormModal with scope selector, dollar amount, warn/hard-stop toggles
- Create IncidentList with status filtering and manual resolve action
- Add tabbed navigation (Cost Entries | Policies | Incidents) to costs section
- Export new components from execution barrel file

src/renderer/components/execution/PolicyFormModal.tsx

@@ -0,0 +1,172 @@
+import { useEffect, useState } from "react";
+import type { BudgetPolicyRecord } from "@shared/types";
+import { ActionButton, Input, Modal, Select } from "../ui";
+
+interface PolicyFormModalProps {
+  open: boolean;
+  onClose: () => void;
+  onSaved: () => void;
+  companyId: string;
+  editingPolicy: BudgetPolicyRecord | null;
+  agents: Array<{ id: string; name: string }>;
+  projects: Array<{ id: string; name: string }>;
+}
+
+export function PolicyFormModal({ open, onClose, onSaved, companyId, editingPolicy, agents, projects }: PolicyFormModalProps) {
+  const [scopeType, setScopeType] = useState<"company" | "agent" | "project">("company");
+  const [scopeId, setScopeId] = useState(companyId);
+  const [amountDollars, setAmountDollars] = useState("100");
+  const [warnPercent, setWarnPercent] = useState("80");
+  const [hardStopEnabled, setHardStopEnabled] = useState(true);
+  const [notifyEnabled, setNotifyEnabled] = useState(true);
+  const [saving, setSaving] = useState(false);
+
+  useEffect(() => {
+    if (editingPolicy) {
+      setScopeType(editingPolicy.scopeType);
+      setScopeId(editingPolicy.scopeId);
+      setAmountDollars((editingPolicy.amount / 100).toFixed(2));
+      setWarnPercent(String(editingPolicy.warnPercent));
+      setHardStopEnabled(editingPolicy.hardStopEnabled);
+      setNotifyEnabled(editingPolicy.notifyEnabled);
+    } else {
+      setScopeType("company");
+      setScopeId(companyId);
+      setAmountDollars("100");
+      setWarnPercent("80");
+      setHardStopEnabled(true);
+      setNotifyEnabled(true);
+    }
+  }, [editingPolicy, companyId]);
+
+  useEffect(() => {
+    if (scopeType === "company") {
+      setScopeId(companyId);
+    } else if (scopeType === "agent" && agents.length > 0) {
+      setScopeId(agents[0].id);
+    } else if (scopeType === "project" && projects.length > 0) {
+      setScopeId(projects[0].id);
+    }
+  }, [scopeType, companyId, agents, projects]);
+
+  async function handleSave() {
+    setSaving(true);
+    try {
+      const amountCents = Math.round(parseFloat(amountDollars) * 100);
+      if (Number.isNaN(amountCents) || amountCents <= 0) return;
+
+      const wp = parseInt(warnPercent, 10);
+      if (Number.isNaN(wp) || wp < 1 || wp > 100) return;
+
+      const result = await window.agentCompany.saveBudgetPolicy({
+        companyId,
+        scopeType,
+        scopeId,
+        metric: "billed_cents",
+        windowKind: "calendar_month_utc",
+        amount: amountCents,
+        warnPercent: wp,
+        hardStopEnabled,
+        notifyEnabled,
+        isActive: true,
+      });
+      if (result.ok) {
+        onSaved();
+        onClose();
+      }
+    } finally {
+      setSaving(false);
+    }
+  }
+
+  return (
+    <Modal
+      open={open}
+      onClose={onClose}
+      title={editingPolicy ? "Edit Budget Policy" : "Add Budget Policy"}
+    >
+      <div className="grid gap-4">
+        <Select
+          label="Scope"
+          value={scopeType}
+          onChange={(v) => setScopeType(v as "company" | "agent" | "project")}
+          options={[
+            { value: "company", label: "Company" },
+            { value: "agent", label: "Agent" },
+            { value: "project", label: "Project" },
+          ]}
+        />
+
+        {scopeType === "agent" ? (
+          <Select
+            label="Agent"
+            value={scopeId}
+            onChange={setScopeId}
+            options={agents.map((a) => ({ value: a.id, label: a.name }))}
+          />
+        ) : null}
+
+        {scopeType === "project" ? (
+          <Select
+            label="Project"
+            value={scopeId}
+            onChange={setScopeId}
+            options={projects.map((p) => ({ value: p.id, label: p.name }))}
+          />
+        ) : null}
+
+        <Input
+          label="Monthly Budget (USD)"
+          value={amountDollars}
+          onChange={setAmountDollars}
+          type="number"
+          placeholder="100.00"
+        />
+
+        <Input
+          label="Warning Threshold (%)"
+          value={warnPercent}
+          onChange={setWarnPercent}
+          type="number"
+          placeholder="80"
+        />
+
+        <label className="flex items-center gap-2.5">
+          <input
+            type="checkbox"
+            checked={hardStopEnabled}
+            onChange={(e) => setHardStopEnabled(e.target.checked)}
+            className="h-4 w-4 rounded border-[color:var(--line)] accent-[color:var(--accent)]"
+          />
+          <span className="text-[13px] text-[color:var(--text)]">Enable hard stop (block new runs at 100%)</span>
+        </label>
+
+        <label className="flex items-center gap-2.5">
+          <input
+            type="checkbox"
+            checked={notifyEnabled}
+            onChange={(e) => setNotifyEnabled(e.target.checked)}
+            className="h-4 w-4 rounded border-[color:var(--line)] accent-[color:var(--accent)]"
+          />
+          <span className="text-[13px] text-[color:var(--text)]">Send notifications</span>
+        </label>
+
+        <div className="flex items-center justify-end gap-3 pt-2">
+          <button
+            type="button"
+            className="rounded-[8px] px-4 py-2 text-[13px] font-medium text-[color:var(--muted-strong)] transition hover:text-[color:var(--text)]"
+            onClick={onClose}
+          >
+            Cancel
+          </button>
+          <ActionButton
+            label={saving ? "Saving..." : "Save Policy"}
+            tone="accent"
+            disabled={saving}
+            onClick={() => void handleSave()}
+          />
+        </div>
+      </div>
+    </Modal>
+  );
+}