Epic: #1975

6 providers implement set_status_tx(&mut self, tx: StatusTx) identically:

• compatible.rs:68, gemini/mod.rs:148, router/mod.rs:335
• orchestrator/router.rs:36, orchestrator/mod.rs:83, any.rs:211

Options:

1. Add set_status_tx to LlmProvider trait with default impl
2. Store status_tx in shared ProviderBase struct

Acceptance Criteria:

• Single implementation point for set_status_tx
• All provider tests pass

Complexity: Small | Effort: 1h
Ref: DRY-02