fix(viperc): 浮点常量按目标类型/声明宽度直接出 f32，不再先出 double

- 浮点字面量在 f32 目标（float(1.5) / x: float = 1.5 / f32 形参）下直接物化 f32 常量，
  负号折叠（-c）同口径；去掉旧的「f64 常量 + fptrunc」
- CDefine 浮点条目记录宽度种类（1=f64 / 2=f32）：define PI: float = ... 的使用处
  直接出 f32 常量，与 f32 字面量混算不再被提升成 double（现场 33 处 cvtss2sd）
- 本模块注册 / pyi·vpi 跨模块重解析 / xmod 缓存三处都按注解裁决宽度，保持跨模块一致

App/lib/core/Gen/GenApi.vp

@@ -192,9 +192,17 @@ def cdefine_decl_bits(pool: memhub.MemBuddy*, annot: ast.AST*, value_node: ast.A
 
 
 # ---------------- register_cdefine_double (delegates to TypeGenCDef.register_cdefine_double) ----------------
-def register_cdefine_double(pool: memhub.MemBuddy*, name: str, value: double):
-    """Delegate to gen.register_cdefine_double"""
-    if _g_gen is not None: _g_gen.TypeGenCDef.register_cdefine_double(pool, name, value)
+def register_cdefine_double(pool: memhub.MemBuddy*, name: str, value: double, is_f32: int = 0):
+    """Delegate to gen.register_cdefine_double (is_f32: 1=float 声明，0=double)"""
+    if _g_gen is not None: _g_gen.TypeGenCDef.register_cdefine_double(pool, name, value, is_f32)
+
+
+# ---------------- cdefine_decl_float_bits (delegates to AssignGenMixin.cdefine_decl_float_bits) ----------------
+def cdefine_decl_float_bits(pool: memhub.MemBuddy*, annot: ast.AST*) -> int:
+    """define 声明的**浮点**宽度裁决：注解显式写了 float → 1（f32），double/未写 → 0。
+    跨模块（.vpi 重解析 define 的 AST）注册必须用它，否则使用方把 f32 常量当 double 物化。"""
+    if _g_gen is not None: return _g_gen.AssignGen.cdefine_decl_float_bits(pool, annot)
+    return 0
 
 
 # ---------------- is_cdefine_annotation (delegates to AssignGenMixin.is_cdefine_annotation) ----------------