refactor(backend): unify EnhancedMultiAgentOrchestrator into ConsolidatedOrchestrator (Phase 4) #5037

Context

Follow-up from #4048 (consolidation 5→4). The 4-file target was met, but under the hood we still have two separate orchestrator classes and two runtime singletons:

1. `ConsolidatedOrchestrator` in `autobot-backend/orchestrator.py` — singleton via `get_orchestrator_sync()`
2. `EnhancedMultiAgentOrchestrator` in `autobot-backend/enhanced_orchestration/init.py` — module-level singleton `enhanced_orchestrator`

Both are instantiated at startup. Production code creates instances of both:

• `services/workflow_automation/manager.py:58-59` constructs both side-by-side
• `services/advanced_workflow/step_generator.py` uses `EnhancedMultiAgentOrchestrator` via `get_orchestrator()`

Gaps

Gap 1 — Two classes, same role

`EnhancedMultiAgentOrchestrator` and `ConsolidatedOrchestrator` both plan and execute multi-agent workflows. The split is historical, not architectural. True consolidation means one class.

Gap 2 — 663-line `init.py` (code smell)

In #4048, `enhanced_orchestration/orchestrator.py` was inlined into `enhanced_orchestration/init.py` (663 lines, 2 top-level classes/functions, plus a module-level singleton). This preserves the import surface (`from enhanced_orchestration import enhanced_orchestrator`) but violates the convention that `init.py` should be a re-export layer, not the implementation.

Proposed fix

Option A (preferred, Phase 4 completion): Merge the useful methods from `EnhancedMultiAgentOrchestrator` into `ConsolidatedOrchestrator`. Delete `enhanced_orchestration/init.py`'s class content. Update `api/orchestration.py` and all callers to use `ConsolidatedOrchestrator` exclusively. Delete the `enhanced_orchestration` package if it becomes empty of logic (keep `types.py`, `success_criteria.py`, etc. if still referenced).

Option B (interim if A is too disruptive): Move `EnhancedMultiAgentOrchestrator` out of `init.py` into a named module (e.g., `enhanced_orchestration/multi_agent.py`). Update `init.py` to only re-export. Keeps the two-class status quo but fixes the code-smell.

Acceptance criteria

• Either: exactly one orchestrator class (A), OR `enhanced_orchestration/init.py` is <100 lines of re-exports only (B)
• All existing orchestration tests still pass (`pytest autobot-backend/tests/orchestration/`)
• No stale references to deleted symbols anywhere under `autobot-backend/`

Related

• refactor(backend): consolidate 7 orchestrator files to 4 #3393 (closed) — original consolidation issue
• refactor(backend): complete orchestrator consolidation (7→4 target) #4048 — Phase 2+3 (just merged in PR refactor(backend): consolidate orchestrator files 5→4 (#4048) #5027)