refactor: extract SshKeysPage components

- Extract use-ssh-keys hook for state management
- Extract SSHKeyCreateForm and SSHKeyList components
- Slim SshKeysPage from 277 to ~80 lines

Quality gates: tsc --noEmit passes, npm run build passes

apps/web/src/hooks/use-ssh-keys.ts

@@ -0,0 +1,108 @@
+import { useState } from "react";
+import { createSSHKey, deleteSSHKey, listSSHKeys, signPayload, verifySignature, type SSHKey } from "../api/ssh-keys";
+import { useAsyncData } from "./use-async-data";
+
+export const useSSHKeys = () => {
+  const { data: keys, status, reload: loadKeys } = useAsyncData<SSHKey[]>(listSSHKeys, []);
+  const [newKeyName, setNewKeyName] = useState("");
+  const [generating, setGenerating] = useState(false);
+  const [signPayloads, setSignPayloads] = useState<Record<string, string>>({});
+  const [signatures, setSignatures] = useState<Record<string, string>>({});
+  const [signing, setSigning] = useState<Record<string, boolean>>({});
+  const [verifyPayloads, setVerifyPayloads] = useState<Record<string, string>>({});
+  const [verifySignatures, setVerifySignatures] = useState<Record<string, string>>({});
+  const [verifyResults, setVerifyResults] = useState<Record<string, boolean | null>>({});
+  const [verifying, setVerifying] = useState<Record<string, boolean>>({});
+  const [mutationError, setMutationError] = useState<string | null>(null);
+
+  const safeKeys = keys ?? [];
+
+  async function handleGenerate(e: React.FormEvent) {
+    e.preventDefault();
+    if (!newKeyName.trim()) return;
+    try {
+      setGenerating(true);
+      await createSSHKey({ name: newKeyName.trim() });
+      setNewKeyName("");
+      await loadKeys();
+    } catch {
+      setMutationError("Failed to generate SSH key");
+    } finally {
+      setGenerating(false);
+    }
+  }
+
+  async function handleDelete(keyId: string) {
+    if (!confirm("Are you sure you want to delete this SSH key?")) return;
+    try {
+      await deleteSSHKey(keyId);
+      await loadKeys();
+    } catch {
+      setMutationError("Failed to delete SSH key");
+    }
+  }
+
+  function copyToClipboard(text: string) {
+    navigator.clipboard.writeText(text);
+  }
+
+  async function handleSign(keyId: string) {
+    const payload = signPayloads[keyId];
+    if (!payload?.trim()) return;
+    try {
+      setSigning((prev) => ({ ...prev, [keyId]: true }));
+      const result = await signPayload(keyId, { payload: payload.trim() });
+      setSignatures((prev) => ({ ...prev, [keyId]: result.signature }));
+      setMutationError(null);
+    } catch {
+      setMutationError("Failed to sign payload");
+    } finally {
+      setSigning((prev) => ({ ...prev, [keyId]: false }));
+    }
+  }
+
+  async function handleVerify(keyId: string) {
+    const payload = verifyPayloads[keyId];
+    const signature = verifySignatures[keyId];
+    if (!payload?.trim() || !signature?.trim()) return;
+    try {
+      setVerifying((prev) => ({ ...prev, [keyId]: true }));
+      const result = await verifySignature(keyId, {
+        payload: payload.trim(),
+        signature: signature.trim(),
+      });
+      setVerifyResults((prev) => ({ ...prev, [keyId]: result.valid }));
+      setMutationError(null);
+    } catch {
+      setMutationError("Failed to verify signature");
+    } finally {
+      setVerifying((prev) => ({ ...prev, [keyId]: false }));
+    }
+  }
+
+  return {
+    keys: safeKeys,
+    status,
+    loadKeys,
+    newKeyName,
+    setNewKeyName,
+    generating,
+    mutationError,
+    setMutationError,
+    signPayloads,
+    setSignPayloads,
+    signatures,
+    signing,
+    verifyPayloads,
+    setVerifyPayloads,
+    verifySignatures,
+    setVerifySignatures,
+    verifyResults,
+    verifying,
+    handleGenerate,
+    handleDelete,
+    copyToClipboard,
+    handleSign,
+    handleVerify,
+  };
+};