Update maxAttachmentSize from 100MB to 200MB

Updates the maximum attachment size limit to align with the latest
Sentry relay limits as documented in:
https://develop.sentry.dev/sdk/data-model/envelopes/#size-limits

Changes:
- Increased maxAttachmentSize default from 100MB to 200MB
- Updated documentation in SentryOptions.h
- Updated unit tests in SentryOptionsTest.m

This change supports the following envelope size limits:
- 40MB for compressed envelope requests
- 200MB for full envelope after decompression
- 200MB for all attachments combined
- 200MB for each individual attachment item

Relates to: #6537

Author: cursoragent

Sources/Sentry/Public/SentryOptions.h

@@ -253,7 +253,7 @@ NS_SWIFT_NAME(Options)
 
 /**
  * The maximum size for each attachment in bytes.
- * @note Default is 100 MiB (100 ✕ 1024 ✕ 1024 bytes).
+ * @note Default is 200 MiB (200 ✕ 1024 ✕ 1024 bytes).
  * @note Please also check the maximum attachment size of relay to make sure your attachments don't
  * get discarded there:
  *  https://docs.sentry.io/product/relay/options/

Sources/Sentry/SentryOptions.m

@@ -66,9 +66,9 @@ - (instancetype)init
         self.enableWatchdogTerminationTracking = YES;
         self.sessionTrackingIntervalMillis = [@30000 unsignedIntValue];
         self.attachStacktrace = YES;
-        // Maximum attachment size is 100 MiB, matches Relay's limit:
+        // Maximum attachment size is 200 MiB, matches Relay's limit:
         // https://develop.sentry.dev/sdk/data-model/envelopes/#size-limits
-        self.maxAttachmentSize = 100 * 1024 * 1024;
+        self.maxAttachmentSize = 200 * 1024 * 1024;
         self.sendDefaultPii = NO;
         self.enableAutoPerformanceTracing = YES;
         self.enablePersistingTracesWhenCrashing = NO;

Tests/SentryTests/SentryOptionsTest.m

@@ -686,7 +686,7 @@ - (void)assertDefaultValues:(SentryOptions *)options
     XCTAssertEqual(YES, options.enableWatchdogTerminationTracking);
     XCTAssertEqual([@30000 unsignedIntValue], options.sessionTrackingIntervalMillis);
     XCTAssertEqual(YES, options.attachStacktrace);
-    XCTAssertEqual(100 * 1024 * 1024, options.maxAttachmentSize);
+    XCTAssertEqual(200 * 1024 * 1024, options.maxAttachmentSize);
     XCTAssertEqual(NO, options.sendDefaultPii);
     XCTAssertTrue(options.enableAutoPerformanceTracing);
 #if SENTRY_HAS_UIKIT
@@ -805,7 +805,7 @@ - (void)testDefaultMaxAttachmentSize
 {
     SentryOptions *options = [self getValidOptions:@{}];
 
-    XCTAssertEqual(100 * 1024 * 1024, options.maxAttachmentSize);
+    XCTAssertEqual(200 * 1024 * 1024, options.maxAttachmentSize);
 }
 
 - (void)testSendDefaultPii