fix: honor the filter after the interval in every triggers

[giaBaoJS]

Description

The hx-trigger reference and the polling pattern both show a polling filter written after the interval:

<div hx-get="/status" hx-trigger="every 2s [document.visibilityState === 'visible']">

On four-dev the filter is never evaluated. __parseTriggerSpecs takes every as the event name and passes 2s [document...] to HCON as modifiers, so the filter ends up as a stray modifier key and the element polls unconditionally. Without the space (every 2s[cond], the form the old v2 test used) it is worse: the interval key becomes 2s[cond], parseInterval returns undefined, and setInterval fires every few milliseconds.

The fix moves a filter that follows the every interval onto the event name before parsing, so every 2s [cond] and every 2s[cond] both parse to {name: 'every[cond]', '2s': true} and the filter runs through the same path as click[cond]. every[cond] 2s and plain every 2s parse the same as before.

Corresponding issue: none, the filter syntax is documented in the hx-trigger every section

Testing

• Unit test in __parseTriggerSpecs.js for both spellings.
• Test in hx-trigger.js that polls with a false filter for 100ms, expects no requests, then makes the filter true and expects a request. Without the change it fails with expected 31 to equal +0 (31 requests in 100ms from two 20ms pollers).
• npm test passes in Chromium (1782 passed, 4 skipped).

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (four-dev, since this is htmx 4 source)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded