feat(parser): Phase 285A1.4 & A1.5 - Weak field sugar + Parser hang fix

A1.4: Add sugar syntax `public weak parent` ≡ `public { weak parent }`
A1.5: Fix parser hang on unsupported `param: Type` syntax

Key changes:
- A1.4: Extend visibility parser to handle weak modifier (fields.rs)
- A1.5: Shared helper `parse_param_name_list()` with progress-zero detection
- A1.5: Fix 6 vulnerable parameter parsing loops (methods, constructors, functions)
- Tests: Sugar syntax (OK/NG), parser hang (timeout-based)
- Docs: lifecycle.md, EBNF.md, phase-285a1-boxification.md

Additional changes:
- weak() builtin implementation (handlers/weak.rs)
- Leak tracking improvements (leak_tracker.rs)
- Documentation updates (lifecycle, types, memory-finalization, etc.)

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

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

src/parser/items/static_items.rs

@@ -67,27 +67,9 @@ impl NyashParser {
 
         // パラメータリストをパース
         self.consume(TokenType::LPAREN)?;
-        let mut params = Vec::new();
 
-        while !self.match_token(&TokenType::RPAREN) && !self.is_at_end() {
-            must_advance!(self, _unused, "static function parameter parsing");
-
-            if let TokenType::IDENTIFIER(param) = &self.current_token().token_type {
-                params.push(param.clone());
-                self.advance();
-
-                if self.match_token(&TokenType::COMMA) {
-                    self.advance();
-                }
-            } else if !self.match_token(&TokenType::RPAREN) {
-                let line = self.current_token().line;
-                return Err(ParseError::UnexpectedToken {
-                    found: self.current_token().token_type.clone(),
-                    expected: "parameter name".to_string(),
-                    line,
-                });
-            }
-        }
+        // Phase 285A1.5: Use shared helper to prevent parser hangs on unsupported type annotations
+        let params = crate::parser::common::params::parse_param_name_list(self, "static method")?;
 
         self.consume(TokenType::RPAREN)?;