feat(joinir): Phase 164 Pattern3 (If-Else PHI) validation complete

- Created 4 representative test cases for Pattern3 patterns:
  * test_pattern3_if_phi_no_break.hako - Core Pattern3 (if-else PHI, no break/continue)
  * test_pattern3_skip_whitespace.hako - Pattern3+break style (routed to Pattern2)
  * test_pattern3_trim_leading.hako - Pattern3+break style (routed to Pattern2)
  * test_pattern3_trim_trailing.hako - Pattern3+break style (routed to Pattern2)

- Validated Pattern3_WithIfPhi detection:
  * Pattern routing: Pattern3_WithIfPhi MATCHED confirmed
  * JoinIR lowering: 3 functions, 20 blocks → 8 blocks (successful)
  * [joinir/freeze] elimination: Complete (no errors on any test)

- Clarified pattern classification:
  * Pattern3_WithIfPhi handles if-else PHI without break/continue
  * Loops with "if-else PHI + break" are routed to Pattern2_WithBreak
  * Break takes priority over if-else PHI in pattern detection

- Cumulative achievement (Phase 162-164):
  * Pattern1: 6 loops working ✅
  * Pattern2: 5 loops working ✅
  * Pattern3 (no break): 1 loop working ✅
  * Pattern3+break (as Pattern2): 3 loops working ✅
  * Total: 15 loops covered, zero [joinir/freeze] errors

- Updated CURRENT_TASK.md with Phase 164 section and findings

Next: Phase 165 Pattern4 (continue) validation

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

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

tools/selfhost/test_pattern2_search.hako

@@ -0,0 +1,35 @@
+// Phase 163: Test linear search with break (Pattern2)
+// Simulates: loop(j < len) { if found { break } j++ }
+
+static box Main {
+  main(args) {
+    // Simulate searching for a value in an array
+    local target = "needle"
+    local search_list = new ArrayBox()
+    search_list.push("apple")
+    search_list.push("banana")
+    search_list.push("needle")
+    search_list.push("cherry")
+
+    local j = 0
+    local found = 0
+    local search_len = search_list.length()
+
+    loop(j < search_len) {
+      local item = search_list.get(j)
+      if item == target {
+        found = 1
+        break
+      }
+      j = j + 1
+    }
+
+    if found == 1 {
+      print("Found at index: " + ("" + j))
+    } else {
+      print("Not found")
+    }
+
+    return 0
+  }
+}