Initial commit: NES emulator with GTK4 desktop frontend

Full NES emulation: CPU, PPU, APU, 47 mappers, iNES/NES 2.0 parsing.
GTK4 desktop client with HeaderBar, pixel-perfect Cairo rendering,
drag-and-drop ROM loading, and keyboard shortcuts.
187 tests covering core emulation, mappers, and runtime.

Cargo.toml

@@ -0,0 +1,42 @@
+[package]
+name = "nesemu"
+version = "0.1.0"
+edition = "2024"
+description = "Core NES/Famicom emulation library in Rust"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
+documentation = "https://docs.rs/nesemu"
+keywords = ["nes", "emulator", "famicom", "gamedev"]
+categories = ["emulators", "games"]
+rust-version = "1.85"
+
+[workspace]
+members = [
+    ".",
+    "crates/nesemu-adapter-api",
+    "crates/nesemu-adapter-headless",
+    "crates/nesemu-desktop",
+]
+default-members = ["."]
+resolver = "2"
+
+[dependencies]
+nesemu-adapter-api = { path = "crates/nesemu-adapter-api", optional = true }
+nesemu-adapter-headless = { path = "crates/nesemu-adapter-headless", optional = true }
+
+[features]
+default = []
+adapter-api = ["dep:nesemu-adapter-api"]
+adapter-headless = ["adapter-api", "dep:nesemu-adapter-headless"]
+
+[lints.rust]
+unsafe_code = "forbid"
+unreachable_pub = "warn"
+
+[lints.clippy]
+pedantic = { level = "allow", priority = -1 }
+wildcard_imports = "allow"
+match_same_arms = "allow"
+module_name_repetitions = "allow"
+too_many_lines = "allow"
+needless_pass_by_value = "allow"