Rename ArenaAllocator -> Arena

style.md

@@ -114,7 +114,7 @@ std::string_view response = static_format(arena,
     "\r\n", body);
 
 // Printf-style formatting - runtime flexible
-ArenaAllocator& arena = conn.get_arena();
+Arena& arena = conn.get_arena();
 std::string_view response = format(arena,
     "HTTP/1.1 %d OK\r\n"
     "Content-Length: %zu\r\n"
@@ -154,9 +154,9 @@ int32_t initial_block_size_;
 - **Full encapsulation still applies** - use `private:` sections to hide implementation details and maintain deep, capable structs
 - The struct keyword doesn't mean shallow design - it means interface-first organization for human readers
 ```cpp
-struct ArenaAllocator {
+struct Arena {
   // Public interface first
-  explicit ArenaAllocator(int64_t initial_size = 1024);
+  explicit Arena(int64_t initial_size = 1024);
   void* allocate_raw(int64_t size);
 
 private:
@@ -228,7 +228,7 @@ template <typename T> struct rebind { using type = T*; };
 #include <simdutf.h>
 #include <weaseljson/weaseljson.h>
 
-#include "arena_allocator.hpp"
+#include "arena.hpp"
 #include "commit_request.hpp"
 
 // Never this:
@@ -248,16 +248,16 @@ std::unique_ptr<Parser> parser;
 - **Explicit constructors** to prevent implicit conversions
 - **Delete copy operations** when inappropriate
 ```cpp
-struct ArenaAllocator {
-  explicit ArenaAllocator(int64_t initial_size = 1024);
+struct Arena {
+  explicit Arena(int64_t initial_size = 1024);
 
   // Copy construction is not allowed
-  ArenaAllocator(const ArenaAllocator &source) = delete;
-  ArenaAllocator &operator=(const ArenaAllocator &source) = delete;
+  Arena(const Arena &source) = delete;
+  Arena &operator=(const Arena &source) = delete;
 
   // Move semantics
-  ArenaAllocator(ArenaAllocator &&source) noexcept;
-  ArenaAllocator &operator=(ArenaAllocator &&source) noexcept;
+  Arena(Arena &&source) noexcept;
+  Arena &operator=(Arena &&source) noexcept;
 
 private:
   int32_t initial_block_size_;
@@ -276,7 +276,7 @@ private:
 std::span<const Operation> operations() const { return operations_; }
 void process_data(std::string_view request_data);  // ≤ 16 bytes, pass by value
 void process_request(const CommitRequest& commit_request);  // > 16 bytes, pass by reference
-ArenaAllocator(ArenaAllocator &&source) noexcept;
+Arena(Arena &&source) noexcept;
 ```
 
 ### Template Usage
@@ -353,10 +353,10 @@ auto value = counter; // Implicit - memory ordering not explicit
 - **STL containers with arena allocators require default construction after arena reset** - `clear()` is not sufficient
 ```cpp
 // STL containers with arena allocators - correct reset pattern
-std::vector<Operation, ArenaStlAllocator<Operation>> operations(arena_allocator);
+std::vector<Operation, ArenaStlAllocator<Operation>> operations(arena);
 // ... use container ...
 operations = {};  // Default construct - clear() won't work correctly
-arena_allocator.reset();  // Reset arena memory
+arena.reset();  // Reset arena memory
 ```
 
 ### Resource Management
@@ -364,7 +364,7 @@ arena_allocator.reset();  // Reset arena memory
 - **Move semantics** for efficient resource transfer
 - **Explicit cleanup** methods where appropriate
 ```cpp
-~ArenaAllocator() {
+~Arena() {
   while (current_block_) {
     Block *prev = current_block_->prev;
     std::free(current_block_);
@@ -395,7 +395,7 @@ enum class [[nodiscard]] ParseResult { Success, InvalidJson, MissingField };
 // System failure - abort immediately
 void* memory = std::malloc(size);
 if (!memory) {
-    std::fprintf(stderr, "ArenaAllocator: Memory allocation failed\n");
+    std::fprintf(stderr, "Arena: Memory allocation failed\n");
     std::abort();
 }
 // ... use memory, eventually std::free(memory)
@@ -529,8 +529,8 @@ Connection(struct sockaddr_storage addr, int fd, int64_t id,
 - **SUBCASE** for related test variations
 - **Fresh instances** for each test to avoid state contamination
 ```cpp
-TEST_CASE("ArenaAllocator basic allocation") {
-  ArenaAllocator arena;
+TEST_CASE("Arena basic allocation") {
+  Arena arena;
 
   SUBCASE("allocate zero bytes returns nullptr") {
     void *ptr = arena.allocate_raw(0);