feat(runtime): Task 15 Phase 1 — decouple Studio dataflow lifecycle from Dora CLI

[vivekrajsingh04]

Files affected:

• mofa-dora-bridge/src/controller.rs
• mofa-dora-bridge/src/error.rs
• mofa-dora-bridge/src/lib.rs
• mofa-dora-bridge/examples/runtime_backend_demo.rs
• mofa-dora-bridge/examples/README.md

Summary

This issue tracks Task 15 (Phase 1) from GSoC: preparing MoFA Studio to migrate from Dora-dependent lifecycle execution toward mofa-rs native runtime.

Today, DataflowController is tightly coupled to Dora CLI lifecycle commands (dora up/start/list/stop).
For migration, we need a runtime abstraction seam while keeping current behavior stable.

Problem

Current lifecycle methods are Dora-specific:

• daemon management assumes Dora (dora up)
• start/stop/status use Dora CLI directly
• no explicit runtime backend model in controller API

This makes native-runtime migration invasive and risky.

Proposed Fix (Phase 1)

1. Introduce runtime backend abstraction in controller:
   • RuntimeBackend::{DoraCli, MofaNative}
   • DataflowController::new_with_runtime(...)
   • runtime_backend() getter
2. Keep default behavior unchanged:
   • DataflowController::new(...) uses RuntimeBackend::DoraCli
3. Add explicit error for unimplemented backend paths:
   • BridgeError::UnsupportedRuntime(...)
4. Add practical usage example:
   • mofa-dora-bridge/examples/runtime_backend_demo.rs
   • mofa-dora-bridge/examples/README.md
5. Add tests for phase-1 guarantees:
   • backend selection is persisted
   • MofaNative start path fails explicitly (not silently)

Validation

• cargo check -p mofa-dora-bridge
• cargo check -p mofa-dora-bridge --example runtime_backend_demo
• cargo test -p mofa-dora-bridge controller::tests::new_with_runtime_sets_backend -- --nocapture
• cargo test -p mofa-dora-bridge controller::tests::mofa_native_start_is_explicitly_unsupported_for_now -- --nocapture
• Example dry run:
  • cargo run -p mofa-dora-bridge --example runtime_backend_demo -- apps/mofa-fm/dataflow/voice-chat.yml
• Example native-backend explicit error:
  • MOFA_RUNTIME_BACKEND=mofa-native cargo run -p mofa-dora-bridge --example runtime_backend_demo -- apps/mofa-fm/dataflow/voice-chat.yml --start

Scope

This is Phase 1 only (abstraction + example + tests).
Actual mofa-rs native lifecycle wiring for MofaNative is planned in follow-up phase(s).

I would like to work on this issue.
GitHub username: @vivekrajsingh04

[vivekrajsingh04]

🟢 [I WANT IT]

I opened this issue and I would like to work on it.
GitHub username: @vivekrajsingh04
Please assign me.

[mandeepsingh2007]

/assign