Adapt HealthChat to upstream v26.10.0

Follow-ups needed after rebasing the HealthChat series from v26.07.0 onto
v26.10.0 that span several of the replayed commits:

- Rename the five PreviewParameterProvider subclasses in features/healthchat
  to the *PreviewParam suffix now enforced by Konsist.
- Rename MemberDirectoryEvents and HealthChatProfileSectionEvents to the
  *Event suffix used by every upstream sealed interface.
- Import FakeStartDMAction from features/startchat/test, where it lives now.
- ListItem lost its headlineContent parameter in favour of content.
- HomeView gained onAddAccountClick and onSwitchToAccount, and onRoomClick
  now carries an EventId; update HomeViewBackHandlingTest accordingly.
- Restore upstream's codecov-action pin (v7.1.1) that the CI squash carried
  back to v7.0.0.
- Gate the new pr-checks.yml on the upstream repository: this fork does not
  use the PR- label convention.
- Add the 26.10.0 section to HEALTHCHAT_CHANGES.md.

features/healthchat/api/src/main/kotlin/io/element/android/features/healthchat/api/directory/MemberDirectoryEvent.kt

@@ -10,17 +10,17 @@ package io.element.android.features.healthchat.api.directory
 
 import io.element.android.libraries.matrix.api.user.MatrixUser
 
-sealed interface MemberDirectoryEvents {
+sealed interface MemberDirectoryEvent {
     /**
      * Fired by the view on first composition. The tab presenter runs from app start (it is
      * composed by the Home presenter), so the first fetch is deferred until the tab is shown.
      */
-    data object LoadIfNeeded : MemberDirectoryEvents
+    data object LoadIfNeeded : MemberDirectoryEvent
 
     /** Header refresh and "try again" — one load path. */
-    data object Refresh : MemberDirectoryEvents
+    data object Refresh : MemberDirectoryEvent
 
-    data class StartDm(val matrixUser: MatrixUser) : MemberDirectoryEvents
+    data class StartDm(val matrixUser: MatrixUser) : MemberDirectoryEvent
 
-    data object ClearStartDmState : MemberDirectoryEvents
+    data object ClearStartDmState : MemberDirectoryEvent
 }

features/healthchat/api/src/main/kotlin/io/element/android/features/healthchat/api/directory/MemberDirectoryState.kt

@@ -18,7 +18,7 @@ data class MemberDirectoryState(
     val searchQuery: TextFieldState,
     val directory: AsyncData<HealthChatMemberDirectory>,
     val startDmActionState: AsyncAction<RoomId>,
-    val eventSink: (MemberDirectoryEvents) -> Unit,
+    val eventSink: (MemberDirectoryEvent) -> Unit,
 ) {
     /** Unknown-while-loading counts as approved so no banner flashes during the first load. */
     val isApproved: Boolean

features/healthchat/api/src/main/kotlin/io/element/android/features/healthchat/api/directory/MemberDirectoryStateFixtures.kt

@@ -25,7 +25,7 @@ fun aMemberDirectoryState(
     searchQuery: TextFieldState = TextFieldState(),
     directory: AsyncData<HealthChatMemberDirectory> = AsyncData.Success(aMemberDirectory()),
     startDmActionState: AsyncAction<RoomId> = AsyncAction.Uninitialized,
-    eventSink: (MemberDirectoryEvents) -> Unit = {},
+    eventSink: (MemberDirectoryEvent) -> Unit = {},
 ) = MemberDirectoryState(
     searchQuery = searchQuery,
     directory = directory,