fix+refactor: soft keywords as identifiers, full test wiring, ORC crash docs

- parser: clause keywords (header, format, status, user, csv, ...) now work
  as identifiers everywhere; IMPORT/EXPORT accept FORMAT csv/HEADER true
- nimble test + CI run all 13 test suites (650 checks green)
- ExecutionContext.registry is now {.cursor.} (breaks registry<->ctx cycle)
- ORC crash reproduced and bisected (tests/orc_repro.py); ARC stays the MM

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
 
       - name: Run tests
         run: |
-          nim c -d:ssl --threads:on --path:src -r tests/test_all.nim > test_output.log 2>&1
+          nimble test > test_output.log 2>&1
           EXIT=$?
           tail -n 200 test_output.log
           exit $EXIT
@@ -52,12 +52,6 @@ jobs:
       - name: Compile benchmarks
         run: nim c -d:release --threads:on benchmarks/bench_all.nim
 
-      - name: Compile stress test
-        run: nim c -d:ssl --threads:on --path:src tests/stress_test.nim
-
-      - name: Run stress test
-        run: ./tests/stress_test
-
       - name: Check for unused declarations and imports
         run: |
           nim c -d:ssl --threads:on --path:src tests/test_all.nim 2>&1 | tee build.log || true