refactor(ariadne): flatten Rust source layout

AGENTS.md

@@ -99,6 +99,8 @@
 - When creating a pull request from a worktree-specific development branch, create a dedicated pull-request branch
   separate from the branch that names or anchors the worktree.
   Do not open pull requests directly from the worktree branch.
+- Ariadne uses a flat Rust source layout under `src/ariadne/`.
+  Do not add a Cargo-default nested `src/ariadne/src/` source directory.
 - In Bazel `BUILD` files, depend on vendored Rust crates through the public aliases under
   `//third_party/crates`, for example `//third_party/crates:serde`.
 - Ariadne extraction must preserve the game-root season prefix for archived source.

src/ariadne/BUILD

@@ -4,9 +4,9 @@ rust_library(
     name = "ariadne_lib",
     crate_name = "ariadne",
     srcs = [
-        "src/artifact.rs",
-        "src/graph.rs",
-        "src/lib.rs",
+        "artifact.rs",
+        "graph.rs",
+        "lib.rs",
     ],
     deps = [
         "//third_party/crates:serde",
@@ -16,7 +16,7 @@ rust_library(
 
 rust_test(
     name = "ariadne_lib_test",
-    srcs = ["src/lib_test.rs"],
+    srcs = ["lib_test.rs"],
     deps = [
         ":ariadne_lib",
         "//third_party/crates:serde_json",
@@ -26,7 +26,7 @@ rust_test(
 rust_binary(
     name = "ariadne",
     crate_name = "ariadne_cli",
-    srcs = ["src/main.rs"],
+    srcs = ["main.rs"],
     deps = [":ariadne_lib"],
 )
 

src/ariadne/Cargo.toml

@@ -3,6 +3,13 @@ name = "ariadne"
 version = "0.1.0"
 edition = "2024"
 
+[lib]
+path = "lib.rs"
+
+[[bin]]
+name = "ariadne"
+path = "main.rs"
+
 [dependencies]
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"