v0.7.0: V2 Standard Error Codes & Cross-Runtime Compliance

What's New

V2 Standard Error Codes

• 13-variant StandardErrorCode enum (E1001-E9999) aligned with AI-Protocol V2
• from_provider_code(), from_error_class(), from_http_status() converters
• Each code carries retryable(), fallbackable(), category() metadata

Feature Flags

• 7 Cargo features: embeddings, batch, guardrails, tokens, telemetry, routing_mvp, interceptors
• full meta-feature for convenience
• Core feedback types always compiled; telemetry sinks feature-gated

Cross-Runtime Compliance

• Compliance test runner against ai-protocol test suite
• 20/20 test cases passing

Optimizations

• Eliminate duplicate error_code_from_body() calls in error paths
• Attach V2 StandardErrorCode directly to ErrorContext
• Optimize format_context() to single-buffer write (reduce heap allocations)
• Add standard_code to structured logging for observability

Documentation

• Chinese one-line description on all module doc headers
• Strengthened .gitignore patterns

Bug Fixes

• Fix batch/collector.rs unclosed delimiter causing build failure with --all-features