fix(sdk): unbreak typecheck on dev after v2 error widening

[kitlangton]

Summary

dev has been red since commit 0e118d1961 (chore: generate following #28495). Two distinct issues:

1. @hey-api/openapi-ts SseFn miswiring (latent for ~9 months)

In every generated client bundle, the SDK declares:

type SseFn = <TData, TError, ...>(options) => Promise<ServerSentEventsResult<TData, TError>>
//                                                                                  ^^^^^^

But ServerSentEventsResult<TData, TReturn = void, TNext = unknown> — that second slot is the underlying AsyncGenerator's return value type, not an error channel. HTTP errors are thrown from the initial promise or surfaced via onSseError; an async generator's .return() value has nothing to do with them.

Confirming this is the SDK's own bug, not intentional:

• The SSE implementation itself declares ServerSentEventsResult<TData> (no TError) — see client-core/bundle/serverSentEvents.ts:80-92.
• The inner generator is async function* with no explicit return → real TReturn is void.
• Same bug in all six generated clients (fetch / axios / ky / next / ofetch / angular). Introduced by d43ef3f3b ("feat(client): add support for server-sent events", Aug 2025).

While the v2 GlobalEventErrors union was effectively empty/unknown this was harmless. PR #28495 widened error responses to concrete types, and now every .return(undefined) call and every mock async generator violates the iterator's TReturn contract:

src/cli/cmd/run/stream.transport.ts(421,43): TS2345: Argument of type 'undefined' is not assignable to parameter of type 'GlobalEventErrors | PromiseLike<GlobalEventErrors>'.
src/cli/cmd/run/stream.transport.ts(426,37): TS2345: ...
test/cli/run/stream.transport.test.ts(169,3): TS2322: Type 'AsyncGenerator<GlobalEvent, void>' is not assignable to type 'AsyncGenerator<GlobalEvent, GlobalEventErrors>'.
test/cli/run/stream.transport.test.ts(1095,9): TS2322: ...
test/cli/run/stream.transport.test.ts(1196,9): TS2322: ...

Fix: drop TError from the ServerSentEventsResult<> generics in our generated packages/sdk/js/src/v2/gen/client/types.gen.ts so TReturn defaults to void. Because @hey-api/openapi-ts runs with clean: true and would overwrite that file on every regen, add a post-gen patch step to packages/sdk/js/script/build.ts that reapplies the fix automatically (and throws if the upstream output shape ever changes, so we'll notice). The phantom TError parameter on SseFn is preserved to keep call-site type-argument arity intact.

I'll open an upstream PR to hey-api/openapi-ts separately so we can drop this workaround when it ships.

2. workspace.warp 400 union widened to include InvalidRequestError

Real consumer bug, separate from #1. ExperimentalWorkspaceWarpErrors is now WorkspaceWarpError | VcsApplyError | InvalidRequestError. The first two discriminate via name, but InvalidRequestError uses _tag (mixed conventions in the SDK). The dialog narrowed via result.error.name === "VcsApplyError" and now hits:

src/cli/cmd/tui/component/dialog-workspace-create.tsx(111,24): TS2339: Property 'name' does not exist on type 'InvalidRequestError | VcsApplyError | WorkspaceWarpError'.

Fix: narrow with "name" in result.error && result.error.name === "VcsApplyError" before reading. Behavior unchanged — InvalidRequestError continues to fall through to the toast path, same as any other non-VcsApplyError.

Test plan

• bun run typecheck (full monorepo) — green
• bun run build in packages/sdk/js after reverting the patched line to the buggy upstream form — confirms post-gen patch reapplies after a real createClient wipe + regen
• bun run test test/cli/run/stream.transport.test.ts — 21/21 pass