revert: drop the Rust port of the Swift macOS app (phase 9)

Reverts 4861015 ("feat(macos): foundation of the macOS app ported from
Swift to Rust"). Decision with the user: keep Ghostty's original Swift
macOS app unchanged and link it against the Rust core instead of the
Zig core. The Rust libghostty exports the identical include/ghostty.h
ABI (ABI-checked), so the Swift app does not need to be rewritten; a
second, Rust-based macOS app would duplicate it without being runnable
or testable here.

Cargo.lock

@@ -1611,27 +1611,6 @@ dependencies = [
  "tempfile",
 ]
 
-[[package]]
-name = "ghostty-macos"
-version = "0.1.0"
-dependencies = [
- "bitflags 2.13.2",
- "block2",
- "dispatch2",
- "ghostty-lib",
- "libc",
- "log",
- "objc2",
- "objc2-app-kit",
- "objc2-core-foundation",
- "objc2-core-graphics",
- "objc2-foundation",
- "objc2-metal",
- "objc2-quartz-core",
- "objc2-user-notifications",
- "tempfile",
-]
-
 [[package]]
 name = "ghostty-onig"
 version = "0.1.0"
@@ -2791,7 +2770,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08849bbd4767dfae9457696856ae1c84fe4e0281bbe4a7abff2d0e06fb7981f8"
 dependencies = [
  "objc2-encode",
- "objc2-exception-helper",
 ]
 
 [[package]]
@@ -2876,16 +2854,6 @@ dependencies = [
  "objc2-foundation",
 ]
 
-[[package]]
-name = "objc2-core-location"
-version = "0.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ca347214e24bc973fc025fd0d36ebb179ff30536ed1f80252706db19ee452009"
-dependencies = [
- "objc2",
- "objc2-foundation",
-]
-
 [[package]]
 name = "objc2-core-text"
 version = "0.3.2"
@@ -2921,15 +2889,6 @@ version = "4.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ef25abbcd74fb2609453eb695bd2f860d389e457f67dc17cafc8b8cbc89d0c33"
 
-[[package]]
-name = "objc2-exception-helper"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7a1c5fbb72d7735b076bb47b578523aedc40f3c439bea6dfd595c089d79d98a"
-dependencies = [
- "cc",
-]
-
 [[package]]
 name = "objc2-foundation"
 version = "0.3.2"
@@ -2988,19 +2947,6 @@ dependencies = [
  "objc2-metal",
 ]
 
-[[package]]
-name = "objc2-user-notifications"
-version = "0.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9df9128cbbfef73cda168416ccf7f837b62737d748333bfe9ab71c245d76613e"
-dependencies = [
- "bitflags 2.13.2",
- "block2",
- "objc2",
- "objc2-core-location",
- "objc2-foundation",
-]
-
 [[package]]
 name = "objc_id"
 version = "0.1.1"