BREAKING CHANGE: The client will now fail the connection (emitting an
error and not reconnecting) if the buffer reaches 100 MB without seeing
a valid, complete EventSource line. Client can be configured by passing
a custom `maxBufferSize`, but ideally the server would emit smaller
chunks and/or use newlines more frequently.

BREAKING CHANGE: Library now requires node.js version 22.19 or higher.
Technically speaking it still supports older engines, but it will not be
guaranteed going forward since Node 20 is out of LTS.

BREAKING CHANGE: Drop separate CommonJS variant. Node.js 22.19 and
higher transparently allows `require(esm)`, so this shouldn't be a
breaking change for most people - but marking it as such in an abudance
of caution. Dropping the CommonJS variant lowers the risk of the "dual
package hazard".

BREAKING CHANGE: Support for Chrome < 84, Safari < 15, Firefox < 105 and
Edge < 84 dropped. This also includes any other javascript environment
that does not support private fields, methods and accessors.

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

A pending reconnection timer would keep the Node.js (and Bun) event loop
alive, preventing the process from exiting while waiting to reconnect.
Calling `unref()` on the timer opts out of that.

The call is feature-checked: browsers and Deno return a numeric timer
handle with no `unref()`, so it is only invoked when available.

…ener

The `onopen`/`onmessage`/`onerror` property handlers were previously stored
separately and invoked directly, before `dispatchEvent()`. That made them
always fire before any listener added via `addEventListener()`, regardless of
the order in which they were registered.

Per the HTML spec, an event handler IDL attribute fires in the order it was
set, relative to other event listeners. The setters now register/unregister
the handler via `addEventListener()`/`removeEventListener()` and the manual
invocations have been removed, so dispatch order now follows the spec.

BREAKING CHANGE: When both an `on*` property handler and an
`addEventListener()` listener are registered for the same event, they now fire
in registration order rather than always firing the `on*` handler first. Code
that relied on the old ordering may observe a different sequence of callbacks.