[Fiona2016]

Problem

Every event uploaded by the Electron SDK reached the intake with an empty environment, whatever env was given to init. The intake reads the environment from the request's ddtags query parameter, not from the event body, and the SDK built a bare …/api/v2/rum with no query; env was only used by the SDK's own tracing and remote-configuration requests. This predates 0.4.0.

Fix

• The upload URL carries ?ddtags=env%3A<env> when env is set: https://<site>/api/v2/rum?ddtags=env%3Aproduction, or behind a proxy <proxy>?ddforward=%2Fapi%2Fv2%2Frum%3Fddtags%3Denv%253Aproduction, since the intake reads its query parameters from inside ddforward.
• Only env is sent. The intake takes service and version from each event — which matters for renderer events, which carry their own service — so neither is put on the request. Commas and colons in the value are replaced with _, as the intake splits tags on them.
• Without an env, the URL is unchanged.
• Renderer events are uploaded by the main process, so they carry the tag too.

Testing

• Unit: 1035 passed (vitest), including the URL built directly and via proxy, the inner query decodable from ddforward, no tag without env, and the sanitized value. Typecheck, e2e typecheck and prettier pass; ESLint reports only the two pre-existing errors in untouched files.
• Playwright: 93/93. The fake intake now records each request's query as the real intake reads it; the contract scenario asserts ddtags=env:test on a main-process event, and the bridge-window scenario asserts it on a renderer-relayed view.

Docs

README describes the query in both the direct and the proxy form, and notes that a proxy endpoint must forward the path and query found in ddforward. CHANGELOG gains a ## [0.4.1] section under 🐛 Bug Fixes with this fix and the stored-remote-configuration fix (#32). package.json is not bumped.