feat: Phase 2.4 NyRT→NyKernel Architecture Revolution 100%完了！

ChatGPT5 Pro設計分析による42%コード削減の完全実現：
- crates/nyrt → crates/nyash_kernel 完全移行
- with_legacy_vm_args系統11箇所削除（encode/birth/future/invoke系）
- Plugin-First Architecture統一（VM依存根絶）
- libnyash_kernel.a生成成功（0エラー・0警告）
- LLVM統合更新（build_llvm.sh, ny-llvmc対応）

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

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

crates/nyash_kernel/src/plugin/console.rs

@@ -0,0 +1,153 @@
+// ---- ExternCall helpers for LLVM lowering ----
+// Exported as: nyash.console.log(i8* cstr) -> i64
+#[export_name = "nyash.console.log"]
+pub extern "C" fn nyash_console_log_export(ptr: *const i8) -> i64 {
+    if ptr.is_null() {
+        return 0;
+    }
+    unsafe {
+        let c = std::ffi::CStr::from_ptr(ptr);
+        if let Ok(s) = c.to_str() {
+            println!("{}", s);
+        }
+    }
+    0
+}
+
+// Exported as: nyash.console.log_handle(i64 handle) -> i64
+#[export_name = "nyash.console.log_handle"]
+pub extern "C" fn nyash_console_log_handle(handle: i64) -> i64 {
+    use nyash_rust::jit::rt::handles;
+    eprintln!("DEBUG: handle={}", handle);
+    if let Some(obj) = handles::get(handle) {
+        let s = obj.to_string_box().value;
+        println!("{}", s);
+    } else {
+        eprintln!("DEBUG: handle {} not found in registry", handle);
+        println!("{}", handle);
+    }
+    0
+}
+
+// Exported as: nyash.console.warn_handle(i64 handle) -> i64
+#[export_name = "nyash.console.warn_handle"]
+pub extern "C" fn nyash_console_warn_handle(handle: i64) -> i64 {
+    if handle <= 0 {
+        return 0;
+    }
+
+    if let Some(obj) = nyash_rust::jit::rt::handles::get(handle) {
+        let s = obj.to_string_box().value;
+        eprintln!("WARN: {}", s);
+    } else {
+        eprintln!("WARN: {}", handle);
+    }
+    0
+}
+
+// Exported as: nyash.console.error_handle(i64 handle) -> i64
+#[export_name = "nyash.console.error_handle"]
+pub extern "C" fn nyash_console_error_handle(handle: i64) -> i64 {
+    if handle <= 0 {
+        return 0;
+    }
+
+    if let Some(obj) = nyash_rust::jit::rt::handles::get(handle) {
+        let s = obj.to_string_box().value;
+        eprintln!("ERROR: {}", s);
+    } else {
+        eprintln!("ERROR: {}", handle);
+    }
+    0
+}
+
+// Exported as: nyash.debug.trace_handle(i64 handle) -> i64
+#[export_name = "nyash.debug.trace_handle"]
+pub extern "C" fn nyash_debug_trace_handle(handle: i64) -> i64 {
+    if handle <= 0 {
+        return 0;
+    }
+
+    if let Some(obj) = nyash_rust::jit::rt::handles::get(handle) {
+        let s = obj.to_string_box().value;
+        eprintln!("TRACE: {}", s);
+    } else {
+        eprintln!("TRACE: {}", handle);
+    }
+    0
+}
+
+// Exported as: nyash.console.warn(i8* cstr) -> i64
+#[export_name = "nyash.console.warn"]
+pub extern "C" fn nyash_console_warn_export(ptr: *const i8) -> i64 {
+    if ptr.is_null() {
+        return 0;
+    }
+    unsafe {
+        let c = std::ffi::CStr::from_ptr(ptr);
+        if let Ok(s) = c.to_str() {
+            eprintln!("[warn] {}", s);
+        }
+    }
+    0
+}
+
+// Exported as: nyash.console.error(i8* cstr) -> i64
+#[export_name = "nyash.console.error"]
+pub extern "C" fn nyash_console_error_export(ptr: *const i8) -> i64 {
+    if ptr.is_null() {
+        return 0;
+    }
+    unsafe {
+        let c = std::ffi::CStr::from_ptr(ptr);
+        if let Ok(s) = c.to_str() {
+            eprintln!("[error] {}", s);
+        }
+    }
+    0
+}
+
+// Exported as: nyash.debug.trace(i8* cstr) -> i64
+#[export_name = "nyash.debug.trace"]
+pub extern "C" fn nyash_debug_trace_export(ptr: *const i8) -> i64 {
+    if ptr.is_null() {
+        return 0;
+    }
+    unsafe {
+        let c = std::ffi::CStr::from_ptr(ptr);
+        if let Ok(s) = c.to_str() {
+            eprintln!("[trace] {}", s);
+        }
+    }
+    0
+}
+
+// Exported as: nyash.console.readline() -> i8*
+#[export_name = "nyash.console.readline"]
+pub extern "C" fn nyash_console_readline_export() -> *mut i8 {
+    use std::io;
+    // Read a line from stdin; normalize to UTF-8 and strip trailing CR/LF
+    let mut input = String::new();
+    // Use read_to_end if stdin is not a TTY? Simpler: read_line through BufRead
+    // For simplicity, read from stdin into buffer until newline or EOF
+    let mut buf = String::new();
+    // Note: use std::io::stdin() directly without an unused handle binding
+    // On failure or EOF, return empty string
+    match io::stdin().read_line(&mut buf) {
+        Ok(_n) => {
+            input = buf;
+        }
+        Err(_) => {
+            input.clear();
+        }
+    }
+    while input.ends_with('\n') || input.ends_with('\r') {
+        input.pop();
+    }
+    // Allocate C string (null-terminated)
+    let mut bytes = input.into_bytes();
+    bytes.push(0);
+    let boxed = bytes.into_boxed_slice();
+    let raw = Box::into_raw(boxed) as *mut u8;
+    raw as *mut i8
+}