perf: use jsonStringifyFast for faster JSON serialization (#25733)

## Summary

Apply the same optimization technique from PR #25717 (Response.json) to
other APIs that use JSON.stringify internally:

- **IPC message serialization** (`ipc.zig`) - used for inter-process
communication
- **console.log with %j format** (`ConsoleObject.zig`) - commonly used
for debugging
- **PostgreSQL JSON/JSONB types** (`PostgresRequest.zig`) - database
operations
- **MySQL JSON type** (`MySQLTypes.zig`) - database operations
- **Jest %j/%o format specifiers** (`jest.zig`) - test output formatting
- **Transpiler tsconfig/macros** (`JSTranspiler.zig`) - build
configuration

### Root Cause

When calling `JSONStringify(globalObject, value, 0)`, the space
parameter `0` becomes `jsNumber(0)`, which is NOT `undefined`. This
causes JSC's FastStringifier (SIMD-optimized) to bail out:

```cpp
// In WebKit's JSONObject.cpp FastStringifier::stringify()
if (!space.isUndefined()) {
    logOutcome("space"_s);
    return { };  // Bail out to slow path
}
```

Using `jsonStringifyFast` which passes `jsUndefined()` triggers the fast
path.

### Expected Performance Improvement

Based on PR #25717 results, these changes should provide ~3x speedup for
JSON serialization in the affected APIs.

## Test plan

- [x] Debug build compiles successfully
- [x] Basic functionality verified (IPC, console.log %j, Response.json)
- [x] Existing tests pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>

src/bun.js/ConsoleObject.zig

@@ -1629,11 +1629,11 @@ pub const Formatter = struct {
                         },
 
                         .j => {
-                            // JSON.stringify the value
+                            // JSON.stringify the value using FastStringifier for SIMD optimization
                             var str = bun.String.empty;
                             defer str.deref();
 
-                            try next_value.jsonStringify(global, 0, &str);
+                            try next_value.jsonStringifyFast(global, &str);
                             this.addForNewLine(str.length());
                             writer.print("{f}", .{str});
                         },

src/bun.js/api/JSTranspiler.zig

@@ -165,7 +165,8 @@ pub const Config = struct {
                 }
 
                 if (!kind.isStringLike()) {
-                    try tsconfig.jsonStringify(globalThis, 0, &out);
+                    // Use jsonStringifyFast for SIMD-optimized serialization
+                    try tsconfig.jsonStringifyFast(globalThis, &out);
                 } else {
                     out = try tsconfig.toBunString(globalThis);
                 }
@@ -204,7 +205,8 @@ pub const Config = struct {
                 defer out.deref();
                 // TODO: write a converter between JSC types and Bun AST types
                 if (is_object) {
-                    try macros.jsonStringify(globalThis, 0, &out);
+                    // Use jsonStringifyFast for SIMD-optimized serialization
+                    try macros.jsonStringifyFast(globalThis, &out);
                 } else {
                     out = try macros.toBunString(globalThis);
                 }

src/bun.js/ipc.zig

@@ -229,7 +229,9 @@ const json = struct {
 
     pub fn serialize(writer: *bun.io.StreamBuffer, global: *jsc.JSGlobalObject, value: JSValue, is_internal: IsInternal) !usize {
         var out: bun.String = undefined;
-        try value.jsonStringify(global, 0, &out);
+        // Use jsonStringifyFast which passes undefined for the space parameter,
+        // triggering JSC's SIMD-optimized FastStringifier code path.
+        try value.jsonStringifyFast(global, &out);
         defer out.deref();
 
         if (out.tag == .Dead) return IPCSerializationError.SerializationFailed;

src/bun.js/test/jest.zig

@@ -430,7 +430,8 @@ pub fn formatLabel(globalThis: *JSGlobalObject, label: string, function_args: []
                 'j', 'o' => {
                     var str = bun.String.empty;
                     defer str.deref();
-                    try current_arg.jsonStringify(globalThis, 0, &str);
+                    // Use jsonStringifyFast for SIMD-optimized serialization
+                    try current_arg.jsonStringifyFast(globalThis, &str);
                     const owned_slice = bun.handleOom(str.toOwnedSlice(allocator));
                     defer allocator.free(owned_slice);
                     bun.handleOom(list.appendSlice(owned_slice));

src/sql/mysql/MySQLTypes.zig

@@ -486,7 +486,8 @@ pub const Value = union(enum) {
 
             .MYSQL_TYPE_JSON => {
                 var str: bun.String = bun.String.empty;
-                try value.jsonStringify(globalObject, 0, &str);
+                // Use jsonStringifyFast for SIMD-optimized serialization
+                try value.jsonStringifyFast(globalObject, &str);
                 defer str.deref();
                 return Value{ .string = str.toUTF8(bun.default_allocator) };
             },

src/sql/postgres/PostgresRequest.zig

@@ -101,7 +101,8 @@ pub fn writeBind(
             .jsonb, .json => {
                 var str = bun.String.empty;
                 defer str.deref();
-                try value.jsonStringify(globalObject, 0, &str);
+                // Use jsonStringifyFast for SIMD-optimized serialization
+                try value.jsonStringifyFast(globalObject, &str);
                 const slice = str.toUTF8WithoutRef(bun.default_allocator);
                 defer slice.deinit();
                 const l = try writer.length();