fix(link): send QR create options as multipart/form-data

[jaredwray]

Problem

Custom options on QR codes don't work between the SDK and the API. Calling link.createQrCode(code, { title, backgroundColor, color, size }) is rejected by the Hyphen API with HTTP 400 (tracked as #133). A plain createQrCode(code) with no options works, which masked the bug.

Root cause

The API endpoint POST /organizations/:organizationId/link/codes/:codeId/qrs/ consumes multipart/form-data:

• qr.schema.ts declares consumes: ['multipart/form-data']; the body schema validates each text field as a multipart field ({ value }) and the logo as an uploaded file (isFile: true).
• app.ts registers @fastify/multipart with attachFieldsToBody: true, and the route handler reads each field via rawPayload[key].value / rawPayload[key]._buf.

The SDK's createQrCode, however, sent a JSON body with content-type: application/json. When custom options are present, the JSON string values fail the multipart body-schema validation → HTTP 400. With no options the body is empty, so it slips through — which is why only the custom-options path was broken.

Fix (SDK only)

createQrCode now builds a FormData body:

• appends only the options that were provided (title, backgroundColor, color, size);
• uploads logo as a file (base64 is decoded to bytes and sent as a Blob);
• drops the JSON content-type header so fetch sets multipart/form-data with its generated boundary (@cacheable/net passes FormData straight through to fetch).

The apix side is correct as designed (the logo is intentionally a file upload with a 1MB limit), so no API change is needed — the SDK simply now conforms to the documented contract.

Tests

• Updated the request-body unit test to assert on the multipart FormData (field values, the logo Blob contents, and that content-type is left unset).
• Added a no-options case so both branches of every optional field are covered.
• Re-enabled the previously skipped should create a QR code with custom options integration test (resolves Flaky/failing test: should create a QR code with custom options returns HTTP 400 #133).

Verification

• biome check clean; tsc --noEmit clean.
• The new/updated createQrCode unit tests pass and cover the method 100% without network.
• ⚠️ The live integration tests (incl. the re-enabled one) could not be run in this environment because api.hyphen.ai is not in the network egress allowlist (every live call returns 403 Host not in allowlist). They should pass in CI where egress and credentials are configured.

https://claude.ai/code/session_011Cn9uaUZa7n8MsPgBP79Dd

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