fix: C backend, parser, sema, HIR lowering for all examples

- C backend: strip c8/c16/c32 string prefixes in emitted C
- C backend: resolve imports to fully-qualified names (Std_Io_PrintLine)
- Parser: fix infinite loop on < in comparisons vs generic calls
- Parser: fix enum patterns without parens (Option::None)
- Parser: fix match expressions inside blocks
- Sema: extract pattern bindings for match arms
- HIR: lower match expressions to if-else chains with enum tag checks
- HIR/C backend: support block expressions as function return values
- Makefile: add integration tests for all 9 examples
- Add pattern_matching.bux example

Makefile

@@ -3,7 +3,9 @@ SRC := src/main.nim
 OUT := buxc
 BUILD_DIR := build
 
-.PHONY: all build test clean
+EXAMPLES := hello fibonacci factorial structs enums methods algebraic_enums generics pattern_matching
+
+.PHONY: all build dev test clean test-examples
 
 all: build
 
@@ -13,14 +15,40 @@ build:
 dev:
 	$(NIM) c -o:$(OUT) $(SRC)
 
-test: build
+test: build test-examples
 	@echo "Running lexer tests..."
 	$(NIM) c -r tests/lexer_test.nim
+	@echo "Running parser tests..."
+	$(NIM) c -r tests/parser_test.nim
+	@echo "Running sema tests..."
+	$(NIM) c -r tests/sema_test.nim
+	@echo "Running HIR tests..."
+	$(NIM) c -r tests/hir_test.nim
 	@echo "Running integration tests..."
 	./$(OUT) new _test_tmp_pkg
 	./$(OUT) --version
 
+test-examples: build
+	@for ex in $(EXAMPLES); do \
+		echo "=== Testing example: $$ex ==="; \
+		mkdir -p examples_pkg/$$ex/src; \
+		cp examples/$$ex.bux examples_pkg/$$ex/src/Main.bux; \
+		if [ ! -f examples_pkg/$$ex/bux.toml ]; then \
+			echo '[Package]' > examples_pkg/$$ex/bux.toml; \
+			echo 'Name    = "'$$ex'"' >> examples_pkg/$$ex/bux.toml; \
+			echo 'Version = "0.1.0"' >> examples_pkg/$$ex/bux.toml; \
+			echo 'Type    = "bin"' >> examples_pkg/$$ex/bux.toml; \
+			echo '' >> examples_pkg/$$ex/bux.toml; \
+			echo '[Build]' >> examples_pkg/$$ex/bux.toml; \
+			echo 'Output = "Bin"' >> examples_pkg/$$ex/bux.toml; \
+		fi; \
+		(cd examples_pkg/$$ex && timeout 10 ../../$(OUT) run) || exit 1; \
+	done
+	@echo "All examples passed!"
+
 clean:
 	rm -f $(OUT)
 	rm -rf $(BUILD_DIR)
 	rm -rf nimcache
+	rm -rf examples_pkg
+	rm -rf _test_tmp_pkg