test(spec): collections contract (sequences, vectors, lists, maps, sets)

Add behavioral spec suites for the collection API (~180 cases). Writing them
surfaced and fixed real bugs:
- (count nil) errored; now 0 (Clojure semantics)
- (repeat x) and (repeatedly f) — the infinite 1-arg arities — were unsupported;
  now return lazy infinite seqs
- set equality used deep= (representation-sensitive), so a set of map literals
  could differ from an equal set built differently; now value-based (each
  element value-equal to some element of the other)

Known limitation filed: phm-typed maps (from hash-map) used as set elements /
map keys hash by identity (map *literals* are structs and work).

jpm test green.

.beads/issues.jsonl

@@ -12,6 +12,7 @@
 {"_type":"issue","id":"jolt-40n","title":"HIGH: update/update-in/assoc-in fail on map literals (struct)","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:56Z","created_by":"Yogthos","updated_at":"2026-06-04T18:40:42Z","closed_at":"2026-06-04T18:40:42Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-ytt","title":"HIGH: str semantics — (str nil)='nil' should be '', (str :b)='b' should be ':b'","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:56Z","created_by":"Yogthos","updated_at":"2026-06-04T18:33:45Z","closed_at":"2026-06-04T18:33:45Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-9sb","title":"HIGH: destructuring gaps (nested seq, :strs, nested map, fn-param)","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:55Z","created_by":"Yogthos","updated_at":"2026-06-04T18:31:24Z","closed_at":"2026-06-04T18:31:24Z","dependency_count":0,"dependent_count":0,"comment_count":0}
+{"_type":"issue","id":"jolt-do7","title":"phm-typed maps as set elements / map keys hash by identity","description":"A map produced via hash-map/assoc (a Janet table/phm) used as a set element or map key hashes by identity, so #{{:a 1}} (struct elem) != #{(hash-map :a 1)} (phm elem) and such elements aren't retrievable by value. Map literals (structs) work. Needs value-based hashing for phm keys in PHM/PHS. Edge case; spec covers literal-map cases.","status":"open","priority":3,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-05T04:07:50Z","created_by":"Yogthos","updated_at":"2026-06-05T04:07:50Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-7dy","title":"MED: compiler path lacks IFn dispatch (collections-as-fn) — only interpreter fixed","status":"closed","priority":3,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:10:00Z","created_by":"Yogthos","updated_at":"2026-06-04T19:56:36Z","closed_at":"2026-06-04T19:56:36Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-90c","title":"MED: filter/take-while not lazy — infinite-seq (take N (filter p (range))) loops","status":"closed","priority":3,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:10:00Z","created_by":"Yogthos","updated_at":"2026-06-04T18:56:26Z","closed_at":"2026-06-04T18:56:26Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-7n5","title":"MED: REPL display — def/defn should print #'ns/name; lazy-seq printer realizes only head ((0 \u003cfunction\u003e))","status":"closed","priority":3,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:59Z","created_by":"Yogthos","updated_at":"2026-06-04T18:55:11Z","closed_at":"2026-06-04T18:55:11Z","dependency_count":0,"dependent_count":0,"comment_count":0}