feat: bounded self-recursion (transitive closure) for evidence

An evidence whose config contains a chain step referencing ITSELF is now
unrolled at compile time into a bounded transitive closure: a union of paths
— base, hop+base, hop²+base, …, hop^N+base — where `hop` is the recursive
chain's steps before the self-reference and the depth N comes from the
pattern's `limit N` (or the compiler's maxRecursionDepth default, 3). The
base (the evidence's non-recursive statements) is verified as a condition
step at each path's terminal node, so the engine needs no new machinery.

- Chain configs carry the pattern's `limit` as maxDepth.
- resolveEvidenceReferences detects a self-reference (_findSelfReference),
  extracts the base (_extractBase), and unrolls (_unrollRecursiveEvidence).
- Pure recursion with no base case is a compile-time error; mutual cycles
  between distinct evidence remain a compile-time error.

Example: can_access_via = can_access OR (reports_to + can_access_via) up to
the declared limit grants access inherited up a reporting chain.

Tests: Recursion (unroll shape, base + multi-hop grants, depth-limit
enforcement, default depth, pure-recursion error, mutual-cycle guard).

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@arbiter/evidence-dsl",
-  "version": "1.10.0",
+  "version": "1.11.0",
   "description": "Evidence DSL v2 compiler: translates the natural Evidence DSL (ADR-000) into @arbiter/core relation configurations.",
   "license": "ISC",
   "type": "module",