Extend testing skill with Miri, fuzzing, and sanitizers

[AlexMikhalev]

Parent Epic: #62

What

Add advanced verification tool guidance to the testing SKILL.md.

Sections to Add

1. Miri -- Running cargo +nightly miri test to detect undefined behavior, aliasing violations, memory leaks in unsafe code
2. Cargo-fuzz / AFL -- Setting up fuzz targets for parsers and input-processing code, corpus management
3. Sanitizers -- AddressSanitizer (ASan), ThreadSanitizer (TSan), MemorySanitizer (MSan) via RUSTFLAGS
4. Property Testing Deep Dive -- proptest strategies, shrinking, regression files, custom generators

Source Reference

Section 7 (Testing Strategies for Systems Code) from RUST_SYSTEM_PROGRAMMING_BEST_PRACTICES.md

Disciplined Engineering Alignment

Phase	Skill	Advanced Testing Relevance
Research	disciplined-research	Identify unsafe code paths needing Miri; catalogue parser inputs for fuzz corpus seeding
Design	disciplined-design	Specify which verification tools apply to each module; design fuzz harness API
Implementation	disciplined-implementation	Add fuzz targets as implementation steps; integrate sanitizers into test runner config
Verification	disciplined-verification	Primary phase: Miri runs on all unsafe code; TSan on all concurrent code; fuzz campaigns on parsers; property tests on invariants
Validation	disciplined-validation	Confirm fuzz campaigns have adequate coverage; validate no UB in production-like environment

The SKILL.md should note:

• During verification (Phase 4): Miri, TSan, and fuzzing are mandatory gates for unsafe/concurrent code
• During design (Phase 2): specify fuzz corpus strategy and sanitizer requirements upfront
• Cross-reference unsafe code policy in rust-development skill

Relevance to Terraphim

Terraphim's Aho-Corasick automata and text processing pipelines benefit directly from fuzzing and Miri verification.

Acceptance Criteria

• SKILL.md updated with Miri, fuzzing, and sanitizer sections
• Includes practical setup commands and CI integration examples
• Cross-references unsafe code policy in rust-development skill
• Disciplined workflow integration notes included