Epic: #1974

Replace 3 unnecessary Box usages with static dispatch:

1. zeph-tools/tool_orchestrator.rs:31 — Vec<Box<dyn PreExecutionVerifier>> -> enum dispatch
2. zeph-channels/cli.rs:14 — Box<dyn Fn(&str) + Send> -> generic parameter
3. zeph-acp/agent/mod.rs:32 — Arc<dyn Fn(&str) -> Option<AnyProvider>> -> ProviderFactory enum

Acceptance Criteria:

• No heap allocation for pre-execution verifiers
• CliChannel generic over persist function type
• All tests pass

Complexity: Small | Effort: 2h
Ref: TYPE-01