feat(phase285w): Phase 285W-Syntax-0.1 - Reject weak(...) syntax (Parser-level Fail-Fast)

- Parser guard: Reject weak(...) with LPAREN check in parse_unary()
  - Error: "Use 'weak expr', not 'weak(expr)'" (helpful message)
  - Location: src/parser/expressions.rs:248-256
- MIR builder guard: Defense-in-depth for any bypassed cases
  - Location: src/mir/builder/calls/build.rs:37-46
- Rejection test: apps/tests/phase285w_weak_call_rejected.hako
- Smoke test: phase285w_weak_call_rejected_vm.sh (PASS ✅)
- Documentation:
  - EBNF.md: Add ~ (BitNot) to unary operators
  - lifecycle.md: Document weak(expr) as invalid syntax
  - phase-285/README.md: Add Phase 285W-Syntax-0.1 entry

Test results: 5/6 phase285 tests PASS (1 unrelated failure)
SSOT: docs/reference/language/lifecycle.md

Closes: Phase 285W-Syntax-0.1

src/parser/expressions.rs

@@ -245,6 +245,15 @@ impl NyashParser {
         // Phase 285W-Syntax-0: weak <expr> unary operator
         if self.match_token(&TokenType::WEAK) {
             self.advance(); // consume 'weak'
+            // Phase 285W-Syntax-0.1: Reject weak(...) function call syntax
+            if self.match_token(&TokenType::LPAREN) {
+                let line = self.current_token().line;
+                return Err(ParseError::UnexpectedToken {
+                    found: TokenType::LPAREN,
+                    expected: "expression after 'weak' unary operator. Use 'weak expr', not 'weak(expr)'".to_string(),
+                    line,
+                });
+            }
             let operand = self.parse_unary()?; // 再帰的に単項演算をパース
             return Ok(ASTNode::UnaryOp {
                 operator: UnaryOperator::Weak,