test: fold cljs ports into spec; add exceptions spec + gap coverage

Mine the cljs port batteries into the spec layer and delete them (their behavior
is covered by spec; the unique functions they exercised are now specced).
Removed test/integration/ports/ entirely.

New/expanded spec coverage from the mining:
- spec/exceptions-spec: try/catch/finally, throw, ex-info/ex-message/ex-data/ex-cause
- doto, pr-str, keyword/symbol constructors, atom?, dynamic var binding

Two rare edges filed (jolt-...): rethrow of a caught ex-info re-wraps it; var-set
on a dynamic var inside binding no-ops. Core try/catch/ex-info and binding work.

Test layout is now spec (22 files, ~677 cases) / integration / unit / support.
conformance 218/218, jpm test green.

README.md

@@ -98,8 +98,8 @@ Tests are organized in three layers:
   per public API area) that collectively pin down Jolt's defined behavior. This
   is the authoritative description of what Jolt promises.
 - **`test/integration/`** — cross-cutting and regression batteries: the Clojure
-  conformance suite, SCI bootstrap/runtime loading, jank conformance, and ported
-  Clojure/CLJS test batches (`test/integration/ports/`).
+  conformance suite, SCI bootstrap/runtime loading, jank conformance, compile-mode
+  tests, and ported Clojure test batteries.
 - **`test/unit/`** — white-box tests for individual components (reader,
   evaluator, types, persistent collections, regex, compiler).