fix(renderer): sync Redux store during streaming and migrate topic creation to Data API

[DeJeune]

What this PR does

Before this PR:

• Streaming updates (blocks and messages) were only written to the cache service, causing the Redux store to be out of sync during streaming, leading to UI not reflecting real-time streaming state.
• Topic creation in Inputbar used Dexie (db.topics.add) directly, which is being removed in v2.

After this PR:

• StreamingService temporarily dispatches to the Redux store alongside cache updates, keeping the UI in sync during streaming.
• Topic creation uses dataApiService.post('/topics', ...) with the server-returned data, aligning with the v2 Data API architecture.
• A mapLegacyTopicToDto helper bridges the legacy Topic type to CreateTopicDto during migration.

Why we need it and why it was done in this way

The following tradeoffs were made:

• The Redux dispatches in StreamingService are marked as temporary (TODO: temp fix) and will be removed after the full message refactoring is complete. This is a pragmatic bridge to keep the UI working during the v2 migration.

The following alternatives were considered:

• Fully refactoring the message/block rendering to use cache-only — deferred to a later phase.

Breaking changes

None

Special notes for your reviewer

The Redux dispatches in StreamingService are intentionally temporary. They exist to bridge the gap between the new cache-based streaming architecture and the existing Redux-dependent UI components.

Checklist

• PR: The PR description is expressive enough and will help future contributors
• Code: Write code that humans can understand and Keep it simple
• Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Documentation: N/A — internal refactoring, no user-facing changes
• Self-review: I have reviewed my own code

Release note

NONE