phase15: update CLAUDE.md and sync with current progress

- Update phase indicator to Phase 15 (Self-Hosting)
- Update documentation links to Phase 15 resources
- Reflect completion of R1-R5 tasks and ongoing work
- Fix CURRENT_TASK.md location to root directory

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

crates/nyash-next/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "nyash-next"
+version = "0.1.0"
+edition = "2021"
+description = "Next-generation Nyash development crate (separate from legacy src)"
+license = "MIT"
+
+[lib]
+name = "nyash_next"
+path = "src/lib.rs"
+
+[[bin]]
+name = "nyash-next"
+path = "src/main.rs"
+
+[dependencies]
+anyhow = "1.0"
+log = "0.4"
+env_logger = "0.11"
+

crates/nyash-next/src/lib.rs

@@ -0,0 +1,9 @@
+//! nyash-next: Next-generation Nyash crate skeleton.
+//!
+//! This crate is intentionally minimal to keep the legacy `src/` untouched.
+//! Start new modules here while preserving the existing `nyash-rust` crate.
+
+pub fn version() -> &'static str {
+    "0.1.0-dev"
+}
+

crates/nyash-next/src/main.rs

@@ -0,0 +1,5 @@
+fn main() {
+    env_logger::init();
+    println!("nyash-next: workspace skeleton is ready.");
+}
+