refactor(RoomView): first-tier simplifications after the hooks migration

[diegolmello]

Proposed changes

Follow-up to #7482 with the first tier of RoomView simplifications. Stacked on native-34-roomview-hooks so the migration and the cleanups can be reviewed separately.

Performance

• The room record observer writes to the store only when an observed room attribute actually changed, so an incoming message no longer re-renders the root, providers, list, footer and composer. Livechat rooms derive lastMessageFromAgent from last_message inside the same observer to feed the on-hold permission.
• MessageComposer reads send-time values from the store inside the press handler instead of subscribing to five slices.
• useRoomStoreForScreen skips the extra render when the acquired store is unchanged.
• The scroll FAB updates only on a threshold crossing.
• The omnichannel routing config is fetched once per server and cached, instead of on every RightButtons and room-actions mount. The on-hold permission is derived from the room store's lastMessageFromAgent and the omnichannel permissions live in useOmnichannelPermissions.

Bug fixes

• Taking an inquiry reads the workspace version from Redux, so a room whose store was warmed before init no longer hits the removed DDP path.
• Jump to Message invalidates earlier jumps, and cancelling the thread loading overlay stops the thread from opening.
• Debounced onEndReached and readThread are cancelled on unmount. useDebounce now returns the debounced state so .cancel is typed.
• A room whose init fails renders a retryable screen instead of an empty list.
• The route is parsed once at mount into a screen identity; a RoomView pushed without rid or t renders a Room_not_found screen with a Back button instead of an empty room.

One canonical wiring per behavior

• Thread names resolve through fetchThreadName; a removed thread now titles as Message_removed (was Thread on one path).
• One thread-press, one useReactionActions call and one sendRoomMessage wiring per room screen, passed to RoomMessageProvider as room actions.
• MessageRoomStoreProvider / MessageRoomProviderWithSetting collapsed into one provider.
• RoomPlaceholder shell shared by EncryptedRoom, MissingRoomE2EEKey, InvitedRoom and the new RoomLoadFailed.
• Invited, missing-E2EE-key and encrypted rooms are decided in a RoomGate before the room tree mounts; the invalid-route screen sits above the gate and the init-failure screen below it, inside RoomScreen.

Mechanical

• useMessages: DB clause is the only system-message filter, query clauses assembled in one literal, no Q.skip(0), thread record appended without an unconditional clone, shared newer-loader lookup with getLocalAnchor, no double casts.
• Typed Animated.FlatList and roomUpdate instead of @ts-ignore / any.
• Shared footer action button for TakeOrJoin / OnHold; blank-label sentinel removed from LeftButtons.
• Inert message-action store reduced to the action it serves.
• The 8,038-line LoadMore snapshot is replaced by state assertions.

Issue(s)

https://rocketchat.atlassian.net/browse/NATIVE-34

How to test or reproduce

• Open a room and receive messages: the list and composer keep working, and the header title still updates on room rename.
• Omnichannel room with manual on-hold enabled: the Place chat on hold entry in the header menu appears after an agent message and disappears after a visitor message.
• Open a thread from the message tree: the loading overlay shows a Cancel button; open a thread whose parent was deleted: title reads Message_removed.
• Invited room, room with missing E2EE key, encrypted room: screens look the same as before.
• Force a room init failure (offline on a room not in the local DB): the retry screen appears and Try again re-runs init.
• Navigate to RoomView without rid (for example a malformed deep link): the Room not found screen appears and Back returns to the previous screen.
• Omnichannel room: Return to queue and the on-hold button still appear; open a second omnichannel room and confirm no extra routing config request is made.
• Reply in thread from the message action sheet, send a message, react.

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments

Not device-verified yet; unit suites, lint and the React Compiler contract test pass on every commit. useE2EEStatus and useRoomRemoved still peek the store registry because they run above the store provider; moving the provider is left for a later PR, as are the remaining R2/R3/R5/R6 items.

Summary by CodeRabbit

• New Features

  • Added a retry screen when a room fails to load.
  • Added shared placeholders for encrypted, invited, and unavailable rooms.
  • Added dedicated livechat queue and hold availability checks.
  • Improved room and thread navigation, including cancellation of outdated jumps.
  • Added clearer loading and action states in room footers.

• Bug Fixes

  • Improved system-message filtering, scrolling, and debounced action handling.
  • Improved livechat hold availability based on the latest agent message.

• Tests

  • Expanded coverage for room loading, navigation, message loading, and room actions.