feat: add prek pre-commit hooks and dependabot (#1720)

* feat: add prek pre-commit hooks and dependabot

Pre-commit hooks (via prek):
- Basic hygiene: trailing-whitespace, end-of-file-fixer, check-yaml, check-added-large-files, check-merge-conflict
- Security: detect-secrets, zizmor (GitHub Actions audit)
- Linting: shellcheck, actionlint, oxlint, swiftlint
- Formatting: oxfmt, swiftformat

Dependabot:
- npm and GitHub Actions ecosystems
- Grouped updates (production/development/actions)
- 7-day cooldown for supply chain protection

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* docs: add prek install instruction to AGENTS.md

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

scripts/e2e/gateway-network-docker.sh

@@ -102,12 +102,12 @@ ws.send(
 	);
 	const connectRes = await onceFrame((o) => o?.type === \"res\" && o?.id === \"c1\");
 	if (!connectRes.ok) throw new Error(\"connect failed: \" + (connectRes.error?.message ?? \"unknown\"));
-	
+
 	ws.send(JSON.stringify({ type: \"req\", id: \"h1\", method: \"health\" }));
 	const healthRes = await onceFrame((o) => o?.type === \"res\" && o?.id === \"h1\", 10000);
 	if (!healthRes.ok) throw new Error(\"health failed: \" + (healthRes.error?.message ?? \"unknown\"));
 	if (healthRes.payload?.ok !== true) throw new Error(\"unexpected health payload\");
-	
+
 	ws.close();
 	console.log(\"ok\");
 NODE"