release: v4.0.0 - Ruchy 4.0 Book 2.0 Quality Release

## Summary
Major release implementing ruchy-book-2.0 specification with 200-point falsification validation.

## Added
- [BOOK-200] Falsification tooling (200-point Karl Popper framework)
- [PARSER-079] Labeled loops ('label: loop/while/for)
- [BOOK-200-01] Closure scope fix

## Fixed
- [CLIPPY] All warnings resolved
- [STRING-INTERP] :: vs : disambiguation

## Quality Metrics
- Tests: 16,102 passed
- Clippy: 0 warnings
- Ch01: 8/8 @ 180/200 PASS

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: noahgift

CHANGELOG.md

@@ -2,6 +2,34 @@
 
 All notable changes to the Ruchy programming language will be documented in this file.
 
+## [4.0.0] - 2026-01-10
+
+### Ruchy 4.0 - Book 2.0 Quality Release
+
+This release implements the ruchy-book-2.0 specification with comprehensive quality validation.
+
+#### Added
+- **[BOOK-200] Falsification Tooling** - 200-point Karl Popper validation framework
+- **[PARSER-079] Labeled Loops** - Support for `'label: loop/while/for` with `break 'label` and `continue 'label`
+- **[BOOK-200-01] Closure Scope Fix** - Closures now correctly capture outer scope variables
+
+#### Fixed
+- **[CLIPPY] Quality Fixes** - Resolved all clippy warnings including:
+  - `empty_enum` lint name correction
+  - `finish_non_exhaustive()` for Debug impls
+  - Doc comment formatting with backticks
+  - Uninlined format args across computebrick module
+- **[STRING-INTERP] Path Separator Fix** - Don't confuse `::` (path separator) with `:` (format specifier)
+
+#### Quality Metrics
+| Metric | Value |
+|--------|-------|
+| Tests | 16,102 passed |
+| Clippy | 0 warnings |
+| Ch01 Book Examples | 8/8 @ 180/200 PASS |
+
+---
+
 ## [Unreleased]
 
 ### PDCA-070: Test Suite Stabilization (2025-12-09)

Cargo.toml

@@ -158,7 +158,7 @@ assertions_on_constants = "allow"  # Tests assert expected constants
 overly_complex_bool_expr = "allow"  # Tests can have complex conditions
 
 [workspace.package]
-version = "3.213.0"
+version = "4.0.0"
 edition = "2021"
 authors = ["Noah Gift"]
 license = "MIT OR Apache-2.0"