feat(joinir): Phase 286 P3.2 - Pattern5 Plan line (loop(true) + early exit)

- Pattern5InfiniteEarlyExitPlan (Return/Break variants)
- extract_pattern5_plan() for loop(true) literal only
- normalize_pattern5_return(): 5 blocks CFG (header→body→found/step)
- normalize_pattern5_break(): 6 blocks CFG with carrier PHI
- NormalizationPlanBox exclusion for Pattern5-style loops
- Fixtures: phase286_pattern5_{return,break}_min.hako
- quick smoke 154/154 PASS

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/mir/builder/control_flow/joinir/patterns/router.rs

@@ -203,6 +203,10 @@ static PLAN_EXTRACTORS: &[PlanExtractorEntry] = &[
         name: "Pattern7_SplitScan (Phase 273)",
         extractor: PlanExtractorVariant::WithPostLoop(super::pattern7_split_scan::extract_split_scan_plan),
     },
+    PlanExtractorEntry {
+        name: "Pattern5_InfiniteEarlyExit (Phase 286 P3.2)",
+        extractor: PlanExtractorVariant::Simple(super::extractors::pattern5::extract_pattern5_plan),
+    },
     PlanExtractorEntry {
         name: "Pattern8_BoolPredicateScan (Phase 286 P2.4)",
         extractor: PlanExtractorVariant::Simple(super::extractors::pattern8::extract_pattern8_plan),