Phase 22.3: Fix parser infinite loop and Stage-B JSON contamination

Fix A: Stage-B output contamination
- Add NYASH_JSON_ONLY=1 to suppress RC output
- Add awk '/^{/,/^}$/' to extract clean JSON only
- File: tools/hakorune_emit_mir.sh:46-49

Fix B: Parser infinite loop in static method parameters
- Replace must_advance! with explicit match on current_token()
- Ensure forward progress in all branches (IDENTIFIER/COMMA/NEWLINE/RPAREN)
- Add NYASH_PARSER_METHOD_PARAM_STRICT=1 for strict mode (default: tolerant)
- File: src/parser/declarations/static_def/members.rs:79-108

Acceptance criteria:
- Stage-B output has no 'RC:' contamination
- phase2231/hakorune_emit_mir_return42_canary_vm.sh passes (rc=42)
- Existing quick tests remain green (backward compatible)

src/parser/declarations/static_def/members.rs

@@ -77,12 +77,36 @@ pub(crate) fn try_parse_method_or_field(
     p.advance(); // consume '('
     let mut params = Vec::new();
     while !p.match_token(&TokenType::RPAREN) && !p.is_at_end() {
-        crate::must_advance!(p, _unused, "static method parameter parsing");
-        if let TokenType::IDENTIFIER(param) = &p.current_token().token_type {
+        // Peek at the current token to ensure forward progress
+        match p.current_token().token_type {
+            TokenType::IDENTIFIER(ref param) => {
                 params.push(param.clone());
                 p.advance();
             }
-        if p.match_token(&TokenType::COMMA) { p.advance(); }
+            TokenType::COMMA => {
+                p.advance();
+            }
+            TokenType::NEWLINE => {
+                // Stage-3 tolerant mode: allow newlines in parameter list
+                p.advance();
+            }
+            TokenType::RPAREN => {
+                break;
+            }
+            _ => {
+                // Unexpected token handling
+                if std::env::var("NYASH_PARSER_METHOD_PARAM_STRICT").ok().as_deref() == Some("1") {
+                    return Err(ParseError::UnexpectedToken {
+                        found: p.current_token().token_type.clone(),
+                        expected: "parameter identifier, comma, or )".to_string(),
+                        line: p.current_token().line,
+                    });
+                } else {
+                    // Tolerant mode: skip unexpected token to avoid infinite loop
+                    p.advance();
+                }
+            }
+        }
     }
     p.consume(TokenType::RPAREN)?;
     // Allow NEWLINE(s) between ')' and '{' of method body

tools/hakorune_emit_mir.sh

@@ -43,10 +43,10 @@ CODE="$(cat "$IN")"
 
 # 1) Stage‑B: Hako parser emits Program(JSON v0) to stdout
 set +e
-PROG_JSON_OUT=$(NYASH_DISABLE_NY_COMPILER=1 HAKO_DISABLE_NY_COMPILER=1 \
+PROG_JSON_OUT=$(NYASH_JSON_ONLY=1 NYASH_DISABLE_NY_COMPILER=1 HAKO_DISABLE_NY_COMPILER=1 \
                 NYASH_PARSER_STAGE3=1 HAKO_PARSER_STAGE3=1 NYASH_PARSER_ALLOW_SEMICOLON=1 \
                 NYASH_ENABLE_USING=1 HAKO_ENABLE_USING=1 \
-                "$NYASH_BIN" --backend vm "$ROOT/lang/src/compiler/entry/compiler_stageb.hako" -- --source "$CODE" 2>/dev/null)
+                "$NYASH_BIN" --backend vm "$ROOT/lang/src/compiler/entry/compiler_stageb.hako" -- --source "$CODE" 2>/dev/null | awk '/^{/,/^}$/')
 rc=$?
 set -e
 if [ $rc -ne 0 ] || [ -z "$PROG_JSON_OUT" ]; then