reorganize: consolidate demo directories

- Consolidate _demo, _pydemo, _embdemo into single _demo directory structure
- Organize demos by language: _demo/{go,py,c,embed}/
- Categorize demos based on imports:
- Python library demos (py imports) → _demo/py/
- C/C++ library demos (c/cpp imports) → _demo/c/
- Go-specific demos → _demo/go/
- Embedded demos → _demo/embed/
- Move C-related demos (asm*, cabi*, cgo*, linkname, targetsbuild) from go/ to c/
- Update all path references in README.md and GitHub workflows
- Improve demo organization and navigation as requested in #1256

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

_demo/embed/targetsbuild/C/c.go

@@ -0,0 +1,21 @@
+package C
+
+func XhandleHardFault() {
+
+}
+
+func Reset_Handler() {
+
+}
+
+func XhandleInterrupt() {
+
+}
+
+type dyn64 struct {
+	// Fields for dynamic loader
+}
+
+// For nintendo switch
+func X__dynamic_loader(base uintptr, dyn *dyn64) {
+}

_demo/embed/targetsbuild/build.sh

@@ -0,0 +1,180 @@
+#!/bin/bash
+
+# Function to display usage information
+show_usage() {
+	cat << EOF
+Usage: $(basename "$0") [OPTIONS] [TARGET_FILE]
+
+Build targets for llgo across multiple platforms.
+
+OPTIONS:
+    -h, --help      Show this help message and exit
+
+ARGUMENTS:
+    TARGET_FILE     Optional. A text file containing target names, one per line.
+                    Lines starting with # are treated as comments and ignored.
+                    Empty lines are also ignored.
+
+BEHAVIOR:
+    Without TARGET_FILE:
+        - Automatically discovers all targets from ../../targets/*.json files
+        - Extracts target names from JSON filenames
+
+    With TARGET_FILE:
+        - Reads target names from the specified file
+        - Supports comments (lines starting with #)
+        - Ignores empty lines and whitespace
+
+IGNORED TARGETS:
+    The following targets are automatically ignored and not built:
+    atmega1280, atmega2560, atmega328p, atmega32u4, attiny85,
+    fe310, k210, riscv32, riscv64, rp2040
+
+RESULT CATEGORIES:
+    ✅ Successful: Build completed successfully
+    🔕 Ignored: Target is in the ignore list
+    ⚠️  Warned: Build failed with configuration warnings
+    ❌ Failed: Build failed with errors
+
+EXIT CODES:
+    0    All builds successful, ignored, or warned only
+    1    One or more builds failed with errors
+
+EXAMPLES:
+    $(basename "$0")                    # Build all targets from JSON files
+    $(basename "$0") my-targets.txt     # Build targets from file
+    $(basename "$0") --help             # Show this help
+
+TARGET FILE FORMAT:
+    # This is a comment
+    esp32
+    cortex-m4
+
+    # Another comment
+    riscv64
+EOF
+}
+
+# Check for help flag
+if [[ "$1" == "-h" || "$1" == "--help" ]]; then
+	show_usage
+	exit 0
+fi
+
+# Check for invalid number of arguments
+if [ $# -gt 1 ]; then
+	echo "Error: Too many arguments."
+	echo "Use '$(basename "$0") --help' for usage information."
+	exit 1
+fi
+
+# Initialize arrays to store results
+successful_targets=()
+ignored_targets=()
+warned_targets=()
+failed_targets=()
+targets_to_build=()
+
+# Define ignore list
+ignore_list=(
+	"atmega1280"
+	"atmega2560"
+	"atmega328p"
+	"atmega32u4"
+	"attiny85"
+	"fe310"
+	"k210"
+	"riscv32"
+	"riscv64"
+	"rp2040"
+)
+
+# Build the targets list based on input method
+if [ $# -eq 1 ]; then
+	# Read targets from file
+	target_file="$1"
+	if [ ! -f "$target_file" ]; then
+		echo "Error: Target file '$target_file' not found."
+		echo "Use '$(basename "$0") --help' for usage information."
+		exit 1
+	fi
+
+	while IFS= read -r target || [[ -n "$target" ]]; do
+		# Skip empty lines and comments
+		if [[ -z "$target" || "$target" =~ ^[[:space:]]*# ]]; then
+			continue
+		fi
+
+		# Trim whitespace
+		target=$(echo "$target" | xargs)
+		targets_to_build+=("$target")
+	done < "$target_file"
+else
+	# Use targets from *.json files
+	for target_file in ../../../targets/*.json; do
+		# Extract target name from filename (remove path and .json extension)
+		target=$(basename "$target_file" .json)
+		targets_to_build+=("$target")
+	done
+fi
+
+# Process each target
+for target in "${targets_to_build[@]}"; do
+	# Check if target is in ignore list
+	if [[ " ${ignore_list[@]} " =~ " ${target} " ]]; then
+		echo 🔕 $target "(ignored)"
+		ignored_targets+=("$target")
+		continue
+	fi
+
+	output=$(../../../llgo.sh build -target $target -o hello.elf . 2>&1)
+	if [ $? -eq 0 ]; then
+		echo ✅ $target `file hello.elf`
+		successful_targets+=("$target")
+	else
+		# Check if output contains warning messages
+		if echo "$output" | grep -q "does not have a valid LLVM target triple\|does not have a valid CPU configuration"; then
+			echo ⚠️ $target
+			echo "$output"
+			warned_targets+=("$target")
+		else
+			echo ❌ $target
+			echo "$output"
+			failed_targets+=("$target")
+		fi
+	fi
+done
+
+echo ""
+echo "----------------------------------------"
+
+# Output successful targets
+echo "Successful targets (${#successful_targets[@]} total):"
+for target in "${successful_targets[@]}"; do
+	echo "$target"
+done
+
+echo ""
+echo "Ignored targets (${#ignored_targets[@]} total):"
+for target in "${ignored_targets[@]}"; do
+	echo "$target"
+done
+
+echo ""
+echo "Warned targets (${#warned_targets[@]} total):"
+for target in "${warned_targets[@]}"; do
+	echo "$target"
+done
+
+echo ""
+echo "Failed targets (${#failed_targets[@]} total):"
+for target in "${failed_targets[@]}"; do
+	echo "$target"
+done
+
+# Exit with error code if there are any failed targets
+if [ ${#failed_targets[@]} -gt 0 ]; then
+	echo ""
+	echo "Build failed with ${#failed_targets[@]} failed targets."
+	exit 1
+fi

_demo/embed/targetsbuild/empty.go

@@ -0,0 +1,6 @@
+package main
+
+import _ "github.com/goplus/llgo/_demo/embed/targetsbuild/C"
+
+func main() {
+}