feat: Add Kilo Gateway provider (#20212)

* feat: Add Kilo Gateway provider

Add support for Kilo Gateway as a model provider, similar to OpenRouter.
Kilo Gateway provides a unified API that routes requests to many models
behind a single endpoint and API key.

Changes:
- Add kilocode provider option to auth-choice and onboarding flows
- Add KILOCODE_API_KEY environment variable support
- Add kilocode/ model prefix handling in model-auth and extra-params
- Add provider documentation in docs/providers/kilocode.md
- Update model-providers.md with Kilo Gateway section
- Add design doc for the integration

* kilocode: add provider tests and normalize onboard auth-choice registration

* kilocode: register in resolveImplicitProviders so models appear in provider filter

* kilocode: update base URL from /api/openrouter/ to /api/gateway/

* docs: fix formatting in kilocode docs

* fix: address PR review — remove kilocode from cacheRetention, fix stale model refs and CLI name in docs, fix TS2742

* docs: fix stale refs in design doc — Moltbot to OpenClaw, MoltbotConfig to OpenClawConfig, remove extra-params section, fix doc path

* fix: use resolveAgentModelPrimaryValue for AgentModelConfig union type

---------

Co-authored-by: Mark IJbema <mark@kilocode.ai>

src/commands/onboard-provider-auth-flags.ts

@@ -6,6 +6,7 @@ type OnboardProviderAuthOptionKey = keyof Pick<
   | "openaiApiKey"
   | "mistralApiKey"
   | "openrouterApiKey"
+  | "kilocodeApiKey"
   | "aiGatewayApiKey"
   | "cloudflareAiGatewayApiKey"
   | "moonshotApiKey"
@@ -64,6 +65,13 @@ export const ONBOARD_PROVIDER_AUTH_FLAGS: ReadonlyArray<OnboardProviderAuthFlag>
     cliOption: "--openrouter-api-key <key>",
     description: "OpenRouter API key",
   },
+  {
+    optionKey: "kilocodeApiKey",
+    authChoice: "kilocode-api-key",
+    cliFlag: "--kilocode-api-key",
+    cliOption: "--kilocode-api-key <key>",
+    description: "Kilo Gateway API key",
+  },
   {
     optionKey: "aiGatewayApiKey",
     authChoice: "ai-gateway-api-key",