refactor(error): organize errors by epistemic category (B_i/I^B)

[aWN4Y25pa2EK]

Summary

Apply EAE Rust skill to error taxonomy for improved architecture robustness.

• Reorganize M2MError variants into three epistemic groups
• Add helper methods for error classification
• Update CryptoError with consistent documentation

Epistemic Categories

B_i Falsified (Belief Proven Wrong)

Caller's assumption about validity was incorrect. These are "expected" errors.

• SessionNotEstablished, InvalidMessage, Decompression, etc.
• Handling: Validate inputs, don't retry without changes

I^B Materialized (Bounded Ignorance)

External state was unknown until runtime. Inherent uncertainty.

• Network, Upstream, Io, Inference, etc.
• Handling: Retry with backoff, circuit breakers, fallbacks

Security (Policy Violations)

Special category requiring explicit handling.

• SecurityThreat, ContentBlocked
• Handling: Do NOT retry, log for audit

New Helper Methods

impl M2MError {
    pub fn is_retryable(&self) -> bool { ... }
    pub fn is_security_error(&self) -> bool { ... }
    pub fn is_bounded_ignorance(&self) -> bool { ... }
    pub fn is_belief_falsified(&self) -> bool { ... }
}

Files Changed

• src/error.rs - Major refactor with epistemic organization
• src/codec/m2m/crypto/error.rs - Enhanced documentation

Testing

• All 269 tests pass
• Clippy clean
• No API breaking changes (additive only)