[RaphaelFakhri]

Fixes: #566

Proposed Changes

• Match the ce- extension prefix case-insensitively when HTTP.toEvent() parses a binary-mode message.
• Skip known attribute headers in any case (for example Ce-Id) so they are not also added as extensions.
• Add a test for binary messages with mixed-case Ce- headers.

Description

HTTP header names are case-insensitive, and some senders and gateways use canonical header names such as Ce-Myext. parseBinary() reads the spec attributes from the lowercased headers, but looks for extensions in the original headers with a case-sensitive startsWith("ce-"). As a result, an extension sent as Ce-Myext: val is dropped from the event.

The extension name after the prefix keeps its original casing, so the behavior from #420 stays the same: ce-LUNCH still becomes event.LUNCH, and validate() still reports it.

Because the original headers are now matched case-insensitively, the loop also skips headers that map to spec attributes (for example Ce-Id or Ce-Specversion). Without this check they would show up as Id and Specversion extensions.

Tests: npm test (228 passing) and npm run lint pass. The new test fails without the change in src/message/http/index.ts.