#19429: Fix/custom bind host validation

Fixes a config validation mismatch that breaks `configure` when selecting a custom Gateway bind IP. ## Problem When running `openclaw configure` and choosing Gateway bind mode `custom`, the wizard writes: - `gateway.bind = "custom"` - `gateway.customBindHost = "<ip>"` Config validation then fails with: `Config validation failed: gateway: Unrecognized key: "customBindHost"` ## Root cause `GatewayConfig` types and runtime code already support `gateway.customBindHost`, but `OpenClawSchema.gateway` in `src/config/zod-schema.ts` did not include this key. ## Fix - Added `gateway.customBindHost` as an optional string in `src/config/zod-schema.ts`. - Added regression coverage in `src/config/config.schema-regressions.test.ts` to validate: - `{ gateway: { bind: "custom", customBindHost: "172.18.0.4" } }` ## Result `configure` no longer fails after selecting a custom gateway IP, and schema/type/runtime behavior is now aligned. <!-- greptile_comment --> <h3>Greptile Summary</h3> This PR fixes a config validation mismatch introduced by the `.strict()` Zod schema on the `gateway` object: `customBindHost` was already part of the `GatewayConfig` TypeScript type and used throughout the runtime, but was absent from `OpenClawSchema.gateway` in `zod-schema.ts`, causing `openclaw configure` to fail after selecting a custom bind IP. Key changes: - **`src/config/zod-schema.ts`**: Adds the missing `customBindHost: z.string().optional()` field to the gateway Zod schema — the core fix. - **`src/gateway/call.ts`**: Adds client-side URL resolution for `bind: "custom"`, using `node:net`'s `isIPv4` to validate the host before constructing the WebSocket URL, with a silent fallback to loopback on invalid input. - **`src/config/config.schema-regressions.test.ts`**: Adds a regression test to prevent the schema omission from recurring. - **`src/gateway/call.ts` tests**: Adds coverage for the new custom-bind URL resolution path. The fix is minimal, well-targeted, and aligns schema, type, and runtime behavior. The `call.ts` changes add functionality (client-side custom bind host resolution for RPC calls) that was previously broken alongside the schema fix. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge — it is a targeted schema alignment fix with no behavioral regressions. - The change is minimal and fixes a clear, documented omission. The `GatewayConfig` type, runtime code, configure wizard, and all downstream consumers already expected `customBindHost` to exist; the schema was simply missing the field. The added `call.ts` logic correctly validates IPv4 input and falls back gracefully. Tests are appropriate and focused. No security implications, no breaking changes. - No files require special attention. _{Last reviewed commit: f972c02} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->