voice transcription (#3381)

Adds voice transcription on press-and-hold of spacebar.


https://github.com/user-attachments/assets/85039314-26f3-46d1-a83b-8c4a4a1ecc21

---------

Co-authored-by: Codex <199175422+chatgpt-codex-connector[bot]@users.noreply.github.com>
Co-authored-by: David Zbarsky <zbarsky@openai.com>

BUILD.bazel

@@ -1,4 +1,11 @@
 load("@apple_support//xcode:xcode_config.bzl", "xcode_config")
+load("@rules_cc//cc:defs.bzl", "cc_shared_library")
+
+cc_shared_library(
+    name = "clang",
+    deps = ["@llvm-project//clang:libclang"],
+    visibility = ["//visibility:public"],
+)
 
 xcode_config(name = "disable_xcode")