fix(ci): install rustfmt component and build images from source

- Add `rustup component add rustfmt clippy` to CI workflow since
  mise installs the Rust toolchain without these components
- Add BUILD_FROM_SOURCE=1 to publish workflow since the Dockerfile
  expects prebuilt binaries that our workflow doesn't produce

Assisted-By: Claude (Anthropic AI) <noreply@anthropic.com>
Signed-off-by: Paolo Dettori <dettori@us.ibm.com>

Author: pdettori

.github/workflows/kagenti-ci.yml

@@ -23,6 +23,9 @@ jobs:
 
       - uses: jdx/mise-action@v2
 
+      - name: Install Rust components
+        run: rustup component add rustfmt clippy
+
       - name: Cache Rust target and registry
         uses: Swatinem/rust-cache@v2
         with:

.github/workflows/publish.yml

@@ -77,6 +77,7 @@ jobs:
           target: gateway
           push: true
           platforms: linux/amd64,linux/arm64
+          build-args: BUILD_FROM_SOURCE=1
           tags: ${{ steps.meta_retry.outputs.tags || steps.meta.outputs.tags }}
           labels: ${{ steps.meta_retry.outputs.labels || steps.meta.outputs.labels }}
           cache-from: type=gha,scope=gateway
@@ -143,6 +144,7 @@ jobs:
           target: supervisor
           push: true
           platforms: linux/amd64,linux/arm64
+          build-args: BUILD_FROM_SOURCE=1
           tags: ${{ steps.meta_retry.outputs.tags || steps.meta.outputs.tags }}
           labels: ${{ steps.meta_retry.outputs.labels || steps.meta.outputs.labels }}
           cache-from: type=gha,scope=supervisor