Add dependency check to Makefile

Introduce a new `check-dependencies` target that verifies the presence
of required system packages and Go tools on Debian systems. This target
is added as a prerequisite to the `default` build target.

This change improves the developer experience by providing clear,
actionable feedback if necessary dependencies are missing. Instead of
failing with cryptic errors during the build or test phases, the user is
informed upfront and given instructions on how to install the missing
components.

Additionally, fix goimports execution in fmt target. The `$(shell ...)`
make function is evaluated when the Makefile is first parsed, not when a
target is executed. This caused `goimports` to run every time `make` was
invoked, regardless of the specified target, including for unrelated
targets like `make clean`.

Author: ottok

Makefile

@@ -1,4 +1,4 @@
-.PHONY: components server targets
+.PHONY: components server targets check-dependencies
 .DEFAULT_GOAL := default
 
 LANG=C
@@ -37,13 +37,13 @@ FILES   := $$(find . -name "*.go")
 FAILPOINT_ENABLE  := $$(tools/bin/failpoint-ctl enable)
 FAILPOINT_DISABLE := $$(tools/bin/failpoint-ctl disable)
 
-default: check build
+default: check-dependencies check build
 	@# Target: run the checks and then build.
 
 include ./tests/Makefile
 
 # Build TiUP and all components
-build: tiup components
+build: check-dependencies tiup components
 	@# Target: build tiup and all it's components
 
 components: playground client cluster dm server
@@ -105,6 +105,33 @@ clean:
 	@rm -rf cover
 	@rm -rf tests/*/{bin/*.test,logs,cover/*.out}
 
+check-dependencies:
+	@# Target: check for required dependencies on Debian systems
+	@# Use shell commands for OS detection to avoid relying on go env
+	@if [ "$$(uname -s)" != "Linux" ]; then \
+		echo "Skipping dependency check on non-Linux OS: $$(uname -s)"; \
+		exit 0; \
+	fi
+	@if [ ! -f /etc/debian_version ]; then \
+		echo "Skipping dependency check on non-Debian system"; \
+		exit 0; \
+	fi
+	@echo "Checking dependencies on Debian..."; \
+	missing_packages=""; \
+	for pkg in ca-certificates golang git curl; do \
+		dpkg -s $$pkg > /dev/null 2>&1 || missing_packages="$$missing_packages $$pkg"; \
+	done; \
+	if [ -n "$$missing_packages" ]; then \
+		echo "Error: Missing required system packages:$$missing_packages"; \
+		echo "Please install them using: apt install -y$$missing_packages"; \
+		exit 1; \
+	fi
+	@if [[ "$$(go version | cut -c 14-20)" < "1.19" ]]; then \
+	  echo "Error: Go version is too old. Please use Go 1.21 or later."; \
+	  exit 1; \
+	fi
+	@echo "Dependencies check passed."
+
 test: failpoint-enable run-tests failpoint-disable
 	@# Target: run tests with failpoint enabled
 	$(MAKE) -C components/client ${MAKECMDGOALS}
@@ -142,7 +169,7 @@ fmt:
 	@echo "gofmt (simplify)"
 	@gofmt -s -l -w $(FILES) 2>&1
 	@echo "goimports (if installed)"
-	$(shell goimports -w $(FILES) 2>/dev/null)
+	@goimports -w $(FILES) 2>/dev/null || true
 
 tools/bin/revive: tools/check/go.mod
 	@# Target: build revive utility