Use dynamic distro selection for UNIT and INTEGRATION tests

- Pass `distro=arch` from Makefile into test scripts
- Replace hardcoded "arch" references with "${distro}"
- Update test-unit.sh and test-integration.sh to use dynamic image names
- Improve log output to reflect selected distro

https://chatgpt.com/share/6939c98a-d428-800f-8bb8-cf72e80ba80c

Makefile

@@ -45,10 +45,10 @@ build:
 # ------------------------------------------------------------
 
 test-unit: build-missing
-	@bash scripts/test/test-unit.sh
+	@distro=arch scripts/test/test-unit.sh
 
 test-integration: build-missing
-	@bash scripts/test/test-integration.sh
+	@distro=arch scripts/test/test-integration.sh
 
 test-e2e: build-missing
 	@bash scripts/test/test-e2e.sh

scripts/test/test-integration.sh

@@ -2,7 +2,7 @@
 set -euo pipefail
 
 echo "============================================================"
-echo ">>> Running INTEGRATION tests in Arch container"
+echo ">>> Running INTEGRATION tests in ${distro} container"
 echo "============================================================"
 
 docker run --rm \
@@ -13,7 +13,7 @@ docker run --rm \
   -e PKGMGR_DEV=1 \
   -e TEST_PATTERN="${TEST_PATTERN}" \
   --entrypoint bash \
-  "package-manager-test-arch" \
+  "package-manager-test-${distro}" \
   -c '
     set -e;
     git config --global --add safe.directory /src || true;

scripts/test/test-unit.sh

@@ -2,7 +2,7 @@
 set -euo pipefail
 
 echo "============================================================"
-echo ">>> Running UNIT tests in Arch container"
+echo ">>> Running UNIT tests in ${distro} container"
 echo "============================================================"
 
 docker run --rm \
@@ -13,7 +13,7 @@ docker run --rm \
   -e PKGMGR_DEV=1 \
   -e TEST_PATTERN="${TEST_PATTERN}" \
   --entrypoint bash \
-  "package-manager-test-arch" \
+  "package-manager-test-${distro}" \
   -c '
     set -e;
     git config --global --add safe.directory /src || true;