feat: inject release tag as version at build time via build.rs

CNCTL_VERSION env var overrides CARGO_PKG_VERSION at compile time so
cnctl --version prints the date+sha release tag instead of 0.1.0.
The release workflow now sets CNCTL_VERSION to the computed date+sha.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Starefossen

.github/workflows/release.yml

@@ -64,10 +64,13 @@ jobs:
 
       - name: Build
         run: |
+          COMMIT_SHA="${{ github.event.workflow_run.head_sha || github.sha }}"
+          SHORT_SHA="${COMMIT_SHA:0:7}"
+          VERSION="$(date -u +%Y.%m.%d)-${SHORT_SHA}"
           if [ "${{ matrix.cross }}" = "true" ]; then
-            cross build --release --target ${{ matrix.target }}
+            CNCTL_VERSION="$VERSION" cross build --release --target ${{ matrix.target }}
           else
-            cargo build --release --target ${{ matrix.target }}
+            CNCTL_VERSION="$VERSION" cargo build --release --target ${{ matrix.target }}
           fi
         shell: bash
 

build.rs

@@ -0,0 +1,8 @@
+fn main() {
+    // Allow overriding the version at build time (used by CI for date+sha releases).
+    // Usage: CNCTL_VERSION="2026.04.05-abc1234" cargo build --release
+    if let Ok(v) = std::env::var("CNCTL_VERSION") {
+        println!("cargo:rustc-env=CARGO_PKG_VERSION={v}");
+    }
+    println!("cargo:rerun-if-env-changed=CNCTL_VERSION");
+}