Add comprehensive GitHub Copilot configuration

Summary

Add a complete GitHub Copilot configuration for regorus with layered architecture: instructions, knowledge files, skills, role-based agents, CI validation, and architecture documentation.

Reference Implementation

A complete reference implementation exists at branch anakrish:copilot-config. Replicate all new files from that branch exactly. The 47 files have been carefully designed based on deep codebase analysis.

Use gh api repos/anakrish/regorus/git/trees/copilot-config?recursive=1 or browse the branch to discover all files. Then fetch each file content and recreate it in this repository.

Files to Create (47 files)

Instructions (auto-loaded by Copilot)

• .github/copilot-instructions.md — Lean ~5KB orientation document with knowledge file reference table
• .github/copilot-code-review-instructions.md — "Think freely" review guide with severity categories (🔴🟠🟡🔵⚪) and domain context

Knowledge Files (20 files in docs/knowledge/)

Deep institutional knowledge per subsystem (~70KB total):

• value-semantics.md — Value type, Undefined propagation, three-valued logic
• rvm-architecture.md — VM execution modes, frame stack, serialization
• builtin-system.md — Builtin registration, feature gating, OPA conformance
• ffi-boundary.md — Safety across 9 bindings, handles, panic containment
• feature-composition.md — Feature flag interactions, no_std boundary
• error-handling-migration.md — anyhow→thiserror migration strategy
• policy-evaluation-security.md — DoS protection, resource limits
• rego-semantics.md — Evaluation model, undefined propagation, backtracking
• interpreter-architecture.md — Context stack, scope management, rule lifecycle
• compilation-pipeline.md — Scheduler, loop hoisting, destructuring planner
• azure-policy-language.md — Azure Policy evaluation model, effects
• azure-rbac-language.md — RBAC condition interpreter, ABAC builtins
• engine-api.md — Public API surface, add_policy→compile→eval flow
• time-builtins-compat.md — Go time.Parse compatibility
• language-extension-guide.md — Adding new policy languages
• tooling-architecture.md — Language server, linter, analyzer patterns
• causality-and-partial-eval.md — Causality tracking and partial evaluation
• rego-compiler.md — Worklist algorithm, expression codegen, register allocation
• azure-policy-aliases.md — Alias registry, ARM normalization pipeline
• telemetry-and-diagnostics.md — Error traceability, structured diagnostics, cloud-scale telemetry

Agents (16 files in .github/agents/)

Role-based personas with YAML frontmatter (description, tools, user-invocable, argument-hint):

• red-teamer.agent.md — Adversarial thinking, break assumptions
• semantics-expert.agent.md — OPA/Rego correctness, Undefined, three-valued logic
• architect.agent.md — System design, FFI, extensibility, feature flags
• performance-engineer.agent.md — Azure scale, allocations, hot paths
• test-engineer.agent.md — Test coverage, property tests, edge cases
• verification-engineer.agent.md — Formal proofs, invariants, Miri/Z3
• security-auditor.agent.md — Threat models, controls, audit evidence
• reliability-engineer.agent.md — Failure modes, determinism, panic safety
• support-engineer.agent.md — Debuggability, error quality, cloud-scale telemetry
• ci-engineer.agent.md — Pipelines, caching, build speed
• refactorer.agent.md — Cleanup, simplification, automation
• api-steward.agent.md — Semver, 9-binding parity, deprecation
• program-manager.agent.md — Scope, prioritize, customer impact
• demo-engineer.agent.md — Examples, tutorials, showcase
• dx-engineer.agent.md — Contributor & integrator friction
• tech-lead.agent.md — Reconcile all agents, constitutional rules, decide

Skills (6 directories in .github/skills/)

Each contains a SKILL.md with YAML frontmatter:

• thorough-review/SKILL.md — Multi-agent parallel review with cross-agent context protocol
• design-alternatives/SKILL.md — Multi-approach evaluation against 9 dimensions
• add-builtin/SKILL.md — Step-by-step guide for adding a new builtin function
• opa-conformance/SKILL.md — OPA conformance testing workflow
• security-review/SKILL.md — Adversarial threat analysis
• verification/SKILL.md — Miri, property testing, Z3, Verus strategies

CI Workflows

• .github/workflows/copilot-setup-steps.yml — Cloud agent environment: Rust 1.92.0 + clippy + rustfmt + cargo cache
• .github/workflows/copilot-config-validation.yml — YAML syntax, reference checking, staleness detection

Architecture Documentation

• docs/copilot-architecture.md — How all layers connect, extension guide, PR review flow diagram

Implementation Instructions

1. Fetch the complete file listing from anakrish:copilot-config branch
2. For each file, fetch its content from the reference branch
3. Create the file with identical content in this repository
4. Ensure all 47 files are created
5. The commit message should follow conventional commits: feat: add comprehensive GitHub Copilot configuration

Acceptance Criteria

• All 47 files from the reference branch are created with matching content
• copilot-config-validation.yml workflow passes (YAML syntax, references)
• No existing files are modified or deleted
• Copyright headers present on files that need them