Initial buck2 adoption, get CLI building

.buckconfig

@@ -0,0 +1,26 @@
+[cells]
+  root = .
+  prelude = prelude
+  toolchains = toolchains
+  none = none
+
+[cell_aliases]
+  config = prelude
+  ovr_config = prelude
+  fbcode = none
+  fbsource = none
+  fbcode_macros = none
+  buck = none
+
+# Uses a copy of the prelude bundled with the buck2 binary. You can alternatively delete this
+# section and vendor a copy of the prelude to the `prelude` directory of your project.
+[external_cells]
+  prelude = bundled
+
+[parser]
+  target_platform_detector_spec = target:root//...->prelude//platforms:default \
+    target:prelude//...->prelude//platforms:default \
+    target:toolchains//...->prelude//platforms:default
+
+[build]
+  execution_platforms = prelude//platforms:default

.gitignore

@@ -19,4 +19,6 @@ target/
 
 .venv/
 __pycache__/
-.pytest_cache/
+.pytest_cache/
+
+buck-out/

BUCK

@@ -0,0 +1,11 @@
+# A list of available rules and their signatures can be found here: https://buck2.build/docs/prelude/globals/
+
+rust_binary(
+    name = "cli",
+    srcs = glob(["crates/pngme-cli/src/*.rs"]),
+    crate_root = "crates/pngme-cli/src/main.rs",
+    deps = [
+        "root//crates/pngme:library",
+        "//third-party/rust:clap",
+    ],
+)

crates/pngme/BUCK

@@ -0,0 +1,12 @@
+rust_library(
+    name = "library",
+    crate = "pngme_lib",
+    srcs = glob(["src/**/*.rs"]),
+    crate_root = "src/lib.rs",
+    visibility = ["PUBLIC"],
+    deps = [
+        "//third-party/rust:snafu",
+        "//third-party/rust:nom",
+        "//third-party/rust:crc",
+    ],
+)