chore: enable bevy/debug and bevy/track_location by default via dev feature

Cargo features cannot be scoped to a build profile, so add a `dev` feature
that pulls in `bevy/debug` and `bevy/track_location` and make it a default
feature. This surfaces real type names and source locations in ECS panics
(e.g. B0001 query conflicts) for normal `cargo build` / `cargo run` /
`cargo test`, at the cost of a small overhead. Shipping builds opt out
with `--release --no-default-features`.

Removes the now-redundant `[dev-dependencies] bevy = { features = ["debug"] }`
override, since the default feature already covers test builds.

Cargo.toml

@@ -3,12 +3,13 @@ name = "bglga"
 version = "0.1.0"
 edition = "2021"
 
+[features]
+default = ["dev"]
+dev = ["bevy/debug", "bevy/track_location"]
+
 [dependencies]
 bevy = "0.18"
 fastrand = "2.0.1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 dirs = "6"
-
-[dev-dependencies]
-bevy = { version = "0.18", features = ["debug"] }

README.md

@@ -28,6 +28,15 @@ The game features:
 nix develop --command cargo build
 ```
 
+The `dev` cargo feature is enabled by default and turns on `bevy/debug` and
+`bevy/track_location` so ECS panics (e.g. `B0001` query conflicts) report
+real type names and source locations. For a shipping release build, disable
+it:
+
+```
+nix develop --command cargo build --release --no-default-features
+```
+
 ## How to Test
 
 ```