budget: rename Init to snake_case + add PascalCase macro wrappers

Convention says FooInit is a macro at the public surface. Budget had
real functions, BudgetAllocatorInit and BudgetAllocatorInitAligned.
Both return BudgetAllocator by value, so the existing return-by-value
ergonomics callers depend on (BudgetAllocator bp = BudgetAllocatorInit
(...);) carry over unchanged: the macros are thin pass-through
wrappers over the renamed budget_allocator_init / _aligned helpers.

All test callers continue to use the PascalCase name and need no
updates.

Author: brightprogrammer

Include/Misra/Std/Allocator/Budget.h

@@ -104,7 +104,8 @@ extern "C" {
     ///
     /// TAGS: Allocator, Budget, Init
     ///
-    BudgetAllocator BudgetAllocatorInit(void *buf, size buf_bytes, size slot_size);
+    BudgetAllocator budget_allocator_init(void *buf, size buf_bytes, size slot_size);
+#define BudgetAllocatorInit(buf, buf_bytes, slot_size) budget_allocator_init((buf), (buf_bytes), (slot_size))
 
     ///
     /// Initialize a `BudgetAllocator` with an alignment floor. Slot size
@@ -118,7 +119,9 @@ extern "C" {
     ///
     /// TAGS: Allocator, Budget, Init, Alignment
     ///
-    BudgetAllocator BudgetAllocatorInitAligned(void *buf, size buf_bytes, size slot_size, size alignment);
+    BudgetAllocator budget_allocator_init_aligned(void *buf, size buf_bytes, size slot_size, size alignment);
+#define BudgetAllocatorInitAligned(buf, buf_bytes, slot_size, alignment)                                               \
+    budget_allocator_init_aligned((buf), (buf_bytes), (slot_size), (alignment))
 
     ///
     /// Tear down a `BudgetAllocator`. No-op for the backing memory (the

Source/Misra/Std/Allocator/Budget.c

@@ -272,11 +272,11 @@ static BudgetAllocator budget_build(void *buf_in, size buf_bytes, size slot_size
     };
 }
 
-BudgetAllocator BudgetAllocatorInit(void *buf, size buf_bytes, size slot_size) {
+BudgetAllocator budget_allocator_init(void *buf, size buf_bytes, size slot_size) {
     return budget_build(buf, buf_bytes, slot_size, sizeof(void *));
 }
 
-BudgetAllocator BudgetAllocatorInitAligned(void *buf, size buf_bytes, size slot_size, size alignment) {
+BudgetAllocator budget_allocator_init_aligned(void *buf, size buf_bytes, size slot_size, size alignment) {
     return budget_build(buf, buf_bytes, slot_size, alignment);
 }