feat(sticky): add setting to disable sticky pinning on All Discussions page

[gianniguida]

Summary

Adds an admin setting flarum-sticky.pin_sticky_on_all_discussions (default: true) that controls whether stickied discussions are pinned to the top of the All Discussions page. Tag pages are unaffected.

This is the 2.x counterpart of #4607 (1.x). It also restructures PinStickiedDiscussionsToTop so the new toggle is the master gate for /all and only_sticky_unread_discussions becomes subordinate to it.

Motivation

The unread-only floating on /all (introduced via only_sticky_unread_discussions) helps until you have long-lived sticky announcements (rules, FAQs). For new visitors, those sticky are always unread, so they pin permanently and push fresh activity down. Some communities want the option to treat /all purely as latest activity, while keeping sticky pinning inside individual tag pages where it remains useful.

Behavior matrix

pin_on_all = flarum-sticky.pin_sticky_on_all_discussions
only_unread = flarum-sticky.only_sticky_unread_discussions

Page	pin_on_all=true, only_unread=true (default)	pin_on_all=true, only_unread=false	pin_on_all=false
/all	Unread sticky pinned (UNION)	All sticky pinned to top	No pinning — natural last_posted_at order
Tag page	All sticky pinned	All sticky pinned	All sticky pinned (setting irrelevant)
Other filters	No pinning	No pinning	No pinning

When pin_on_all=false, the only_unread setting becomes a no-op — the admin UI greys it out (after save) since the read/unread distinction can't apply to discussions that aren't pinned.

Changes

• extend.php — register pin_sticky_on_all_discussions (default true) and consolidate the three Extend\Settings declarations into a single block.
• src/PinStickiedDiscussionsToTop.php — reorder the __invoke flow so tag pages are handled first, then pin_on_all gates the /all path, then only_unread decides the pinning style. The new ordering keeps tag-page behavior unchanged.
• js/src/admin/extend.tsx — add a boolean toggle for pin_on_all directly above only_unread, and add a disabled predicate on only_unread that reflects the persisted pin_on_all value.
• locale/en.yml — add admin.settings.pin_sticky_on_all_discussions_{label,help}.
• tests/integration/api/ListDiscussionsTest.php — three new tests (see below).

Backwards compatibility

The default value matches existing behavior, so this is a no-op on upgrade. No migration needed. Existing only_sticky_unread_discussions semantics are preserved when pin_on_all is true (the default).

Tests added

• list_discussions_does_not_pin_sticky_on_all_when_pin_setting_disabled_as_guest — pin_on_all=false as guest, expects natural order on /all.
• list_discussions_pin_setting_disabled_overrides_only_unread_setting_on_all — both settings off, authenticated user with unread sticky, still expects natural order — proves master-gate precedence.
• list_discussions_pin_setting_disabled_does_not_affect_tag_pages — pin_on_all=false with a tag filter, expects all sticky pinned — proves the gate is /all-scoped.

All existing tests continue to pass unchanged.

Notes

The admin disabled-state on only_sticky_unread_discussions reads app.data.settings, which reflects persisted values. So the disabled state updates after save. A fully reactive (no-save-needed) version would require a custom component subscribing to the in-progress form stream — left out as a polish item.

Related

• 1.x counterpart: [1.x] feat: add setting to disable sticky pinning on All Discussions page #4607