Refactor to use format for http responses

src/format.hpp

@@ -79,6 +79,8 @@
  * - **Simple concatenation**: Basic string + number + string combinations
  * - **Compile-time optimization**: When all types/values known at compile time
  * - **Template contexts**: Where compile-time buffer sizing is beneficial
+ * - **IMPORTANT**: Only works with compile-time string literals, NOT runtime
+ * const char*
  *
  * ## Optimization Details:
  * The function uses `ArenaAllocator::allocate_remaining_space()` to claim all
@@ -206,10 +208,12 @@ inline constexpr DoubleTerm term(double s) { return DoubleTerm(s); }
  * optimized term writers for maximum speed.
  *
  * ## Supported Types:
- * - **String literals**: C-style string literals and arrays
+ * - **String literals**: C-style string literals and arrays ("Hello", "World")
  * - **Integers**: All integral types (int, int64_t, uint32_t, etc.)
  * - **Floating point**: double (uses high-precision Grisu2 algorithm)
  * - **Custom types**: Via specialization of `detail::term()`
+ * - **NOT supported**: const char* variables, std::string, std::string_view
+ * variables
  *
  * ## Performance Characteristics:
  * - **Compile-time buffer sizing**: Buffer size calculated at compile time (no
@@ -245,16 +249,23 @@ inline constexpr DoubleTerm term(double s) { return DoubleTerm(s); }
  *
  * ## When to Use:
  * - **Hot paths**: Performance-critical code where formatting speed matters
- * - **Known types**: When argument types are known at compile time
+ * - **Compile-time string literals**: All string arguments must be string
+ * literals (e.g., "Hello")
  * - **Simple formatting**: Concatenation and basic type conversion
  * - **Template code**: Where compile-time optimization is beneficial
+ * - **CANNOT use runtime strings**: No const char*, std::string, or string_view
+ * variables
  *
  * ## When to Use format() Instead:
  * - **Printf-style formatting**: When you need format specifiers like "%d",
  * "%.2f"
- * - **Runtime flexibility**: When format strings come from variables/config
- * - **Complex formatting**: When you need padding, precision, etc.
- * - **Convenience**: For quick debugging or non-critical paths
+ * - **Runtime strings**: When you have const char*, std::string, or string_view
+ * variables
+ * - **Dynamic content**: When format strings come from variables/config/user
+ * input
+ * - **Complex formatting**: When you need padding, precision, width specifiers
+ * - **Mixed literal/runtime**: When combining string literals with runtime
+ * string data
  *
  * @note All arguments are passed by forwarding reference for optimal
  * performance