Add knowledge docs, agent definitions, and skill files

Add comprehensive documentation and GitHub Copilot configuration:

- docs/knowledge/: 17 deep-dive knowledge files covering value semantics,
  RVM architecture, builtins, FFI boundary, feature composition, error
  handling migration, policy evaluation security, Rego semantics,
  interpreter/compiler architecture, Azure Policy/RBAC, engine API,
  time builtins, language extension guide, tooling architecture,
  causality/partial eval, Rego compiler, Azure Policy aliases, and
  telemetry/diagnostics

- .github/agents/: 16 role-specific AI agent definitions (red-teamer,
  semantics-expert, architect, performance-engineer, test-engineer,
  verification-engineer, security-auditor, reliability-engineer,
  support-engineer, ci-engineer, refactorer, api-steward, program-manager,
  demo-engineer, dx-engineer, tech-lead)

- .github/skills/: 6 workflow skill definitions (thorough-review,
  design-alternatives, add-builtin, opa-conformance, security-review,
  verification)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: anakrish <35780660+anakrish@users.noreply.github.com>

.github/skills/verification/SKILL.md

@@ -0,0 +1,143 @@
+---
+name: verification
+description: >-
+  Formal verification and memory safety verification for regorus. Use this
+  skill when asked about Miri, formal verification, Z3, Verus, property
+  testing, or when verifying safety properties of regorus code.
+allowed-tools: shell
+---
+
+# Verification Skill
+
+regorus uses multiple verification approaches to ensure correctness and
+memory safety. This skill guides verification efforts.
+
+## Verification Tiers
+
+### Tier 1: Miri (Active — in CI)
+
+Miri detects undefined behavior in unsafe code, memory leaks, and
+concurrency bugs. regorus runs Miri in CI.
+
+```bash
+# Run Miri on the test suite
+cargo +nightly miri test
+
+# Run Miri on specific tests
+cargo +nightly miri test -- test_name
+
+# Run with stricter checks
+MIRIFLAGS="-Zmiri-strict-provenance" cargo +nightly miri test
+```
+
+**What Miri catches:**
+- Use-after-free, double-free
+- Out-of-bounds memory access
+- Uninitialized memory reads
+- Data races (with `-Zmiri-check-stacked-borrows`)
+- Memory leaks
+
+**regorus context:** The core crate is `#![forbid(unsafe_code)]`, so Miri
+is most relevant for FFI binding crates (`bindings/ffi/`) where unsafe is
+allowed. Also useful for verifying `Rc::make_mut()` patterns.
+
+### Tier 2: Property Testing (Recommended)
+
+Use `proptest` or `quickcheck` to test properties that must hold for all
+inputs:
+
+```rust
+use proptest::prelude::*;
+
+proptest! {
+    #[test]
+    fn value_roundtrip(v in arb_value()) {
+        let json = v.to_json_str();
+        let parsed = Value::from_json_str(&json)?;
+        prop_assert_eq!(v, parsed);
+    }
+
+    #[test]
+    fn eval_deterministic(policy in arb_policy(), input in arb_input()) {
+        let r1 = engine.eval(&policy, &input)?;
+        let r2 = engine.eval(&policy, &input)?;
+        prop_assert_eq!(r1, r2);
+    }
+}
+```
+
+**Properties worth testing in regorus:**
+- Value serialization round-trips
+- Evaluation determinism (same input → same output)
+- Interpreter/RVM equivalence (both paths produce same result)
+- Undefined propagation consistency
+- Resource limit enforcement (instruction budget halts execution)
+- RVM program serialization round-trips
+
+### Tier 3: Z3 / SMT Solving (Planned)
+
+For verifying policy properties symbolically:
+
+- **Policy satisfiability**: is there any input that satisfies this policy?
+- **Policy equivalence**: do two policies produce the same result for all inputs?
+- **Policy subsumption**: does policy A imply policy B?
+- **Unreachable rules**: are there rules that can never fire?
+
+This connects to the partial evaluation vision in
+`docs/knowledge/causality-and-partial-eval.md`.
+
+### Tier 4: Verus (Planned)
+
+Verus enables verified Rust — proving properties about Rust code at
+compile time. Potential targets in regorus:
+
+- **Value type invariants**: prove that Value operations preserve type safety
+- **RVM instruction safety**: prove that well-formed programs cannot cause
+  register overflow or invalid memory access
+- **Scheduler correctness**: prove that topological sort produces valid order
+- **Resource limit enforcement**: prove that instruction budget is checked
+
+## Verification Strategies by Subsystem
+
+### Value Type (`src/value.rs`)
+- Property test: all operations handle Undefined correctly
+- Property test: comparison is total ordering
+- Property test: serialization round-trips for all Value variants
+- Miri: Rc::make_mut patterns don't alias
+
+### RVM (`src/rvm/`)
+- Property test: program serialization round-trips
+- Property test: instruction budget halts execution within bounds
+- Property test: register allocation stays within frame bounds
+- Miri: frame stack operations are memory-safe
+
+### FFI (`bindings/ffi/`)
+- Miri: handle create/destroy cycles don't leak
+- Miri: panic containment doesn't cause UB
+- Property test: poisoned engine rejects all operations
+
+### Builtins (`src/builtins/`)
+- Property test: builtins return Undefined (not error) for type mismatches
+- Property test: time parsing matches OPA reference for valid inputs
+- Property test: string operations handle UTF-8 edge cases
+
+## Running Verification
+
+```bash
+# Tier 1: Miri
+cargo +nightly miri test
+
+# Tier 2: Property tests (if added)
+cargo test --test prop_tests
+
+# Full verification suite
+cargo +nightly miri test && cargo test && cargo test --test opa --features opa-testutil
+```
+
+## Reference
+
+- `docs/knowledge/policy-evaluation-security.md` — Security properties to verify
+- `docs/knowledge/value-semantics.md` — Value invariants
+- `docs/knowledge/rvm-architecture.md` — RVM safety properties
+- `docs/knowledge/ffi-boundary.md` — FFI safety requirements
+- `docs/knowledge/causality-and-partial-eval.md` — Symbolic analysis vision