refactor(smoke): Wrap -c inline scripts in main() (Phase 287 P4 Box 2)

File mode SSOT requires all code in declarations (static box/function).
Top-level execution statements will be prohibited in future.

Changed all run_nyash_vm -c scripts to:
- static box Main { main() { ... return 0 } }

Affected tests:
- string_concat.sh (3 test functions)
  - test_variable_concat: wrapped in main()
  - test_number_string_concat: wrapped + explicit .toString()
- multi_branch_phi.sh: wrapped in main()
- vm_loop_phi_multi_carriers.sh: wrapped in main()
- vm_loop_phi_multi_continue.sh: wrapped in main()
- vm_nested_mixed_break_continue.sh: wrapped in main()

This fixes top-level parse errors while maintaining test coverage.

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

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

tools/smokes/v2/profiles/quick/core/phi/multi_branch_phi.sh

@@ -9,20 +9,25 @@ preflight_plugins || exit 2
 
 test_multi_branch_phi() {
   local script='
-local n, s
-n = 3
-if n == 1 {
-  s = "one"
-} else if n == 2 {
-  s = "two"
-} else if n == 3 {
-  s = "three"
-} else if n == 4 {
-  s = "four"
-} else {
-  s = "many"
+static box Main {
+  main() {
+    local n, s
+    n = 3
+    if n == 1 {
+      s = "one"
+    } else if n == 2 {
+      s = "two"
+    } else if n == 3 {
+      s = "three"
+    } else if n == 4 {
+      s = "four"
+    } else {
+      s = "many"
+    }
+    print(s)
+    return 0
+  }
 }
-print(s)
 '
   local output
   output=$(run_nyash_vm -c "$script" 2>&1)

tools/smokes/v2/profiles/quick/core/string_concat.sh

@@ -21,11 +21,16 @@ test_simple_concat() {
 
 test_variable_concat() {
     local script='
-local greeting, name, message
-greeting = "Hello"
-name = "Nyash"
-message = greeting + ", " + name + "!"
-print(message)
+static box Main {
+    main() {
+        local greeting, name, message
+        greeting = "Hello"
+        name = "Nyash"
+        message = greeting + ", " + name + "!"
+        print(message)
+        return 0
+    }
+}
 '
     local output
     output=$(run_nyash_vm -c "$script" 2>&1)
@@ -34,10 +39,15 @@ print(message)
 
 test_number_string_concat() {
     local script='
-local num, text
-num = 42
-text = "The answer is " + num
-print(text)
+static box Main {
+    main() {
+        local num, text
+        num = 42
+        text = "The answer is " + num.toString()
+        print(text)
+        return 0
+    }
+}
 '
     local output
     output=$(run_nyash_vm -c "$script" 2>&1)

tools/smokes/v2/profiles/quick/core/vm_loop_phi_multi_carriers.sh

@@ -7,7 +7,7 @@ preflight_plugins || exit 2
 
 test_multi_carriers_fib6() {
   # Fibonacci with 6 steps starting a=0,b=1 => b ends at 13
-  local code='i=0; a=0; b=1; loop(i<6) { t=a+b; a=b; b=t; i=i+1 }; print(b)'
+  local code='static box Main { main() { local i, a, b, t; i=0; a=0; b=1; loop(i<6) { t=a+b; a=b; b=t; i=i+1 }; print(b); return 0 } }'
   local out
   out=$(run_nyash_vm -c "$code")
   [ "$out" = "13" ]

tools/smokes/v2/profiles/quick/core/vm_loop_phi_multi_continue.sh

@@ -7,11 +7,11 @@ preflight_plugins || exit 2
 
 test_multi_continue_sum() {
   # Expect: sum of odd numbers 1..9 except 7 -> 1+3+5+9 = 18
-  local code='i=0; sum=0; loop(i<10) {
+  local code='static box Main { main() { local i, sum; i=0; sum=0; loop(i<10) {
     if i%2==0 { i=i+1; continue }
     if i==7 { i=i+1; continue }
     sum=sum+i; i=i+1
-  }; print(sum)'
+  }; print(sum); return 0 } }'
   local out
   out=$(run_nyash_vm -c "$code")
   [ "$out" = "18" ]

tools/smokes/v2/profiles/quick/core/vm_nested_mixed_break_continue.sh

@@ -8,13 +8,13 @@ preflight_plugins || exit 2
 test_nested_mixed() {
   # Outer i=0..4, inner j=0..4, skip j==2 (continue), break inner entirely when i==3.
   # Counts per i: 0->4, 1->4, 2->4, 3->0 (break), 4->4 => total 16
-  local code='i=0; sum=0; loop(i<5) {
+  local code='static box Main { main() { local i, j, sum; i=0; sum=0; loop(i<5) {
     j=0; loop(j<5) {
       if j==2 { j=j+1; continue }
       if i==3 { break }
       sum=sum+1; j=j+1
     }; i=i+1
-  }; print(sum)'
+  }; print(sum); return 0 } }'
   local out
   out=$(run_nyash_vm -c "$code")
   [ "$out" = "16" ]