feat: migrate shadowlink topic APIs to dataplane v1alpha3 (#2044)

* refactor: move shadowlink topic APIs to dataplane v1alpha3

Move ListShadowLinkTopics, GetShadowTopic, and GetShadowMetrics
from console v1alpha1 to dataplane v1alpha3 API. Console v1alpha1
now only contains shadowlink CRUD operations (Create, Get, List,
Update, Delete), while dataplane v1alpha3 handles data operations
(topics, metrics, failover).

* build: regenerate proto files for shadowlink API split

* feat: update frontend to use dataplane API for shadowlink topics

Update shadowlink React Query hooks to use dataplane v1alpha3 for
topic operations (list, get) and metrics, while keeping console
v1alpha1 for CRUD operations.

* feat: enhance failover API with 202 status and response data

- Change failover endpoint HTTP status code from 200 to 202 (Accepted)
  to better represent async operation semantics
- Add FailOverResponse fields:
  - name: shadow link that was failed over
  - failed_over_topics: list of topics affected by failover
- Update OpenAPI spec to reflect 202 status code
- Regenerate proto files for backend (Go) and frontend (TypeScript)

The backend will populate failed_over_topics by querying all topics
in the shadowlink when shadow_topic_name is not specified in the request,
or returning just the single topic when shadow_topic_name is provided.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* feat: move GetShadowLink API to dataplane v1alpha3

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Co-authored-by: Claude <[email protected]>

Author: c-julin