feat: add message/channel paginator stack with thread minimal-init and state stores

[MartinCupela]

Summary

This PR is a broader SDK architecture update, not just a message pagination introduction.
In addition to the new paginator stack, it introduces minimal Thread initialization (without initial server thread payload), reactive StateStore-based state in ChannelState, new orchestration/event-pipeline utilities.

What’s included

1) New pagination foundation + message pagination

• Introduces the new paginator system under src/pagination/paginators/*:
  • BasePaginator
  • ChannelPaginator
  • MessagePaginator
  • MessageReplyPaginator
  • ReminderPaginator
• Adds supporting pagination utilities:
  • filter/sort compilers
  • cursor derivation helpers
  • index + normalization utilities
• Adds MessagePaginator integration for channel and thread flows:
  • reply querying through paginator
  • message focus signal support
  • ingest/update/delete/reaction/truncation handling
  • jump-to-message state emission fixes

2) Multi-list channel orchestration

• Adds ChannelPaginatorsOrchestrator for managing multiple channel lists/paginators.
• Adds EventHandlerPipeline for composable/ordered event handling.
• Supports ownership strategies when a channel matches multiple paginators (including priority-based ownership).
• Handles list updates/removals/re-emits across relevant channel events.

3) Thread minimal-init support (no initial thread payload required)

• Thread constructor now supports initialization from:
  • client + channel + parentMessage (with optional draft)
  • or existing threadData
• Enables creating a usable thread instance before full hydration.
• Keeps reload/hydration and pagination bootstrap behavior available after creation.
• Includes broader thread event/state synchronization updates (participants/reply count/read/replies).

4) Reactive ChannelState stores

• Adds StateStore-backed reactive slices in ChannelState:
  • watchers
  • typing
  • read
  • members (+ member count sync)
  • own capabilities
  • muted users
• Preserves existing access patterns while introducing store-backed updates.

5) Message operations + local update flows

• Adds MessageOperations and MessageOperationStatePolicy.
• Adds/expands optimistic local update APIs for Channel/Thread message actions:
  • send
  • retry
  • update
  • delete
• Adds message send retry cache behavior and related test coverage.

6) Config/setup and request customization improvements

• Introduces and exports InstanceConfigurationService.
• Moves setup/config state handling to dedicated configuration module and root exports.
• Adds custom mark-read request support for both Channel and Thread.
• Removes thread parameter from Channel custom mark-read request signature.

Testing

Large test expansion and updates across:

• paginator units (Base, Channel, Message, MessageReply, compiler/index utilities)
• orchestrator + event pipeline
• channel/channel_state/thread behaviors
• message operations + delivery tracking
• composer/text composer interactions
• merge utility behavior

Todo

• internal docs
• docs

[github-actions]

Size Change: +96.3 kB (+23.54%) 🚨

Total Size: 505 kB

📦 View Changed

Filename	Size	Change
dist/cjs/index.browser.js	168 kB	+32.1 kB (+23.57%)	🚨
dist/cjs/index.node.js	170 kB	+32.2 kB (+23.39%)	🚨
dist/esm/index.mjs	167 kB	+32 kB (+23.65%)	🚨

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