build(profiles): make the dev profile suitable for embedded

It is our opinion that the `release` profile should be reserved for
production builds.
This makes the `dev` profile suitable for low-Flash targets we support,
and will allow us to leverage `debug_assert!`s in debug builds.

Documentation of Cargo profiles can be found here:
https://doc.rust-lang.org/cargo/reference/profiles.html

Cargo.toml

@@ -91,12 +91,12 @@ incremental = false
 codegen-units = 1
 debug = true
 lto = false
-opt-level = 1
+opt-level = "s" # Optimize for size even in debug builds
 
 [profile.release]
 incremental = false
 codegen-units = 1
-debug = true
+debug = true # Required for defmt
 lto = false
 opt-level = "s"