vm(hako): add v1 reader/dispatcher (flagged), commonize mir_call handler, share block scan; smokes: add v1 hakovm canary; docs: 20.37/20.38 plans, OOB policy; runner: v1 hakovm toggle; include SKIP summary

src/mir/phi_core/if_phi.rs

@@ -178,8 +178,9 @@ pub fn merge_modified_at_merge_with<O: PhiMergeOps>(
 
         // Build incoming pairs from reachable predecessors only
         let mut inputs: Vec<(crate::mir::BasicBlockId, ValueId)> = Vec::new();
+        // Only include reachable predecessors; do not synthesize else_block when unreachable.
         if let Some(tp) = then_pred_opt { inputs.push((tp, then_v)); }
-        if let Some(ep) = else_pred_opt.or(Some(else_block)) { inputs.push((ep, else_v)); }
+        if let Some(ep) = else_pred_opt { inputs.push((ep, else_v)); }
 
         match inputs.len() {
             0 => {}