docs: explain simulator bridge language choice

Author: thymikee

apple/snapshot-bridge/README.md

@@ -22,3 +22,18 @@ surface.
 
 The private API is intentionally pinned to the idb v1.5.2-compatible shape.
 See `LICENSE.idb` for attribution.
+
+## Why Objective-C
+
+The selected #2192 mechanism was idb v1.5.2's Objective-C
+`SimulatorFrameworkBridge`; the Python used during the spike was only a client
+for exercising that guest reader. This bridge keeps the proven native boundary
+and removes the Python/idb client dependency.
+
+Objective-C is the narrowest implementation for this private runtime adapter:
+it resolves unavailable classes and functions with `dlopen`, `dlsym`, and the
+Objective-C runtime, invokes dynamically discovered selectors, and contains
+`NSException` failures. A Swift implementation would still require an
+Objective-C shim for those operations, adding another native boundary. Keeping
+the guest in Objective-C also allows direct lazy compilation with `clang`
+without an Xcode project or Swift module for private headers.