fix(fetch): type SDK responses from parseAs option

[Dexter2099]

Summary

Fixes #3835.

Threads the fetch client's request-level parseAs option through generated SDK function types so callers get the runtime response shape in data.

For example, parseAs: 'blob' now produces Blob data instead of the OpenAPI schema response type. The default parseAs: 'auto' behavior keeps the existing schema-derived response type.

Most of the diff is generated fixture output from the client, plugin, and example matrices.

Cause

The fetch client runtime already parses responses according to parseAs, but generated SDK functions only passed schema-derived response types into RequestResult. The request-level parse mode was not part of the SDK function generic, client method call, or return type.

Fix

• Add an internal parse-mode generic to fetch client request/result types.
• Map explicit parse modes to their runtime data types.
• Thread TParseAs through fetch SDK options, return types, and client method calls.
• Add compile-time regression coverage and update generated snapshots/examples.

Tests

• corepack pnpm ty @hey-api/openapi-ts
• corepack pnpm ty @test/openapi-ts
• corepack pnpm exec vitest run --project @hey-api/openapi-ts packages/openapi-ts/src/plugins/@hey-api/client-fetch/__tests__
• corepack pnpm exec vitest run --project @test/openapi-ts packages/openapi-ts-tests/main/test/clients.test.ts
• corepack pnpm exec vitest run --project @test/openapi-ts packages/openapi-ts-tests/main/test/plugins.test.ts
• sh ./scripts/examples-check.sh
• targeted eslint on touched source/test files
• targeted oxfmt --check on package diff files

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[changeset-bot]

⚠️ No Changeset found

Latest commit: c1f7775

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[pullfrog]

✅ No new issues found.

Reviewed changes — threads parseAs through the fetch client's RequestResult and SDK function generics so callers get the right data type for each parse mode.

• Add ParsedResponse<TData, TParseAs> conditional type — maps each parseAs literal to its runtime data type (Blob, string, ArrayBuffer, FormData, ReadableStream<Uint8Array> | null for stream, or TData[keyof TData] for json/auto).
• Thread TParseAs through RequestResult, MethodFn, RequestFn, RequestOptions, ResolvedRequestOptions, Client — all the fetch client surface types gain a TParseAs generic defaulting to 'auto'.
• Gate SDK emission behind isFetchClient and !isSse — operationStatements(), operationReturnType(), operationOptionsType(), createTypeOptions(), and v1/node.ts all use $if(isFetchClient, ...) and supportsParseAs = isFetchClient && !isSse so non-fetch clients and SSE operations are untouched.
• Add Config to SDK imports — the generated Options type uses NonNullable<Config['parseAs']> as the TParseAs constraint.
• Add compile-time type assertions — types.test.ts verifies RequestResult produces Blob, string, ArrayBuffer, and the JSON-shaped response type for the corresponding parseAs values.
• Update 30 snapshot files — all mechanical propagation of the new generic across 10 client-fetch snapshot variants.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 38.73%. Comparing base (795a33d) to head (c1f7775).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4075      +/-   ##
==========================================
+ Coverage   38.68%   38.73%   +0.05%     
==========================================
  Files         626      626              
  Lines       21864    21894      +30     
  Branches     6406     6431      +25     
==========================================
+ Hits         8458     8481      +23     
- Misses      10922    10928       +6     
- Partials     2484     2485       +1     

Flag	Coverage Δ
unittests	38.73% <ø> (+0.05%)	⬆️

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commit: c1f7775