Further optimise release speed by using the defaults

Also: optimise for size explicitly.
Note that we don't add debug info as this can blow up compile time
to 1h40m on some platform, Linux if memory serves.

Author: Byron

.github/workflows/publish.yaml

@@ -197,6 +197,7 @@ jobs:
         run: |
           echo "CARGO_PROFILE_RELEASE_LTO=fat" >> $GITHUB_ENV
           echo "CARGO_PROFILE_RELEASE_CODEGEN_UNITS=1" >> $GITHUB_ENV
+          echo "CARGO_PROFILE_RELEASE_OPT_LEVEL=s" >> $GITHUB_ENV
       - name: Build binary
         shell: bash
         run: |

Cargo.toml

@@ -101,8 +101,10 @@ rmcp = { version = "0.1.5" }
 serde_json_lenient = "0.2.3"
 
 [profile.release]
-lto = "thin"      # Enables link to optimizations, but don't go all out on compile time.
-opt-level = "s"   # Optimize for binary size
+# There are no overrides here as we optimise for fast release builds,
+# which are used when building locally and when making Nightly builds.
+# The Stable release builds override the relevant settings at release time
+# to optimise for size.
 
 [profile.bench]
 codegen-units = 256