fix(ios): break retain cycle between renderers and RendererFactory (#284)

Each renderer subclass held a strong reference to RendererFactory,
which itself caches renderers in a strong-keyed dictionary. This created
a retain cycle that ARC could not break, causing the factory and all
renderers (plus their StyleConfig instances) to leak on every props
update.

The fix is to make the renderer's reference to the factory __weak,
matching the pattern already used in ThematicBreakRenderer.m.
AttributedRenderer.m remains strong since it is the actual owner of
the factory.

Verified via Instruments Leaks template before/after: previously the
top of the leak list was dominated by RendererFactory, all renderer
subclasses, and StyleConfig (~9 KiB each); after the fix, none of
these classes appear in the leak list.

Author: mgmx-io

ios/renderer/BlockquoteRenderer.m

@@ -10,7 +10,7 @@
 static NSString *const kNestedInfoRangeKey = @"range";
 
 @implementation BlockquoteRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/CodeBlockRenderer.m

@@ -8,7 +8,7 @@
 #import "StyleConfig.h"
 
 @implementation CodeBlockRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/CodeRenderer.m

@@ -9,7 +9,7 @@
 #import <React/RCTFont.h>
 
 @implementation CodeRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/ENRMImageRenderer.m

@@ -9,7 +9,7 @@
 static const unichar kZeroWidthSpace = 0x200B;
 
 @implementation ENRMImageRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/ENRMMathInlineRenderer.m

@@ -10,7 +10,7 @@
 #if ENRICHED_MARKDOWN_MATH
 
 @implementation ENRMMathInlineRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/ENRMSpoilerRenderer.m

@@ -5,7 +5,7 @@
 #import "RendererFactory.h"
 
 @implementation ENRMSpoilerRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
 }
 
 - (instancetype)initWithRendererFactory:(id)rendererFactory config:(__unused id)config

ios/renderer/EmphasisRenderer.m

@@ -7,7 +7,7 @@
 #import <React/RCTFont.h>
 
 @implementation EmphasisRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/HeadingRenderer.m

@@ -20,7 +20,7 @@
                                           @"heading-4", @"heading-5", @"heading-6"};
 
 @implementation HeadingRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/LinkRenderer.m

@@ -6,7 +6,7 @@
 #import <React/RCTFont.h>
 
 @implementation LinkRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }
 

ios/renderer/ListItemRenderer.m

@@ -21,7 +21,7 @@ - (void)applyCheckedDecorationsTo:(NSMutableAttributedString *)output
 @end
 
 @implementation ListItemRenderer {
-  RendererFactory *_rendererFactory;
+  __weak RendererFactory *_rendererFactory;
   StyleConfig *_config;
 }