perf(pytest): 194s → 4s collection — lazy heavy imports + norecursedirs

Four-part fix for the collection bottleneck that was blocking the dev loop:

1. Lazy mitreattack.stix20 import in attack_stix.py — deferred to first
   _load() call (TYPE_CHECKING guard at top level)

2. Lazy misp_stix_converter import in both MISP export routers — moved
   from module level into the route handler body

3. Lazy attack_catalog / attack_stix in ttp.py repo mixin — thin wrapper
   functions so the import chain never fires at module load time

4. tests/api/conftest.py — `from decnet.web.api import app` moved inside
   the `client()` fixture; `pytest_ignore_collect` broadened to skip all
   test_schemathesis*.py variants (not just test_schemathesis.py), which
   were launching a subprocess server at module-import time

5. pyproject.toml — `norecursedirs` for tests/live, tests/stress,
   tests/service_testing, tests/docker, tests/perf so these directories
   are never entered; `-m` filter removed from addopts (now redundant);
   `--dist loadscope` → `--dist load` to unblock workers immediately

6. behave_core / behave_shell rename — BEHAVE packages dropped the
   `decnet_` prefix; reinstalled editable installs and updated all 14
   import sites across profiler, ttp, bus, and correlation modules

tests/profiler/behave_shell/test_registry_coverage.py

@@ -1,7 +1,7 @@
 """Step H.1: registry-coverage test.
 
 Static assertion that every Tier-A primitive in
-``decnet_behave_shell.spec.primitives.PRIMITIVE_REGISTRY`` has a slot
+``behave_shell.spec.primitives.PRIMITIVE_REGISTRY`` has a slot
 in the calibration-grid binding sets — either the per-shard hard gate
 (``PHASE_ABCDEFG_PRIMITIVES``) or one of the conditional sets
 (``PHASE_D_CONDITIONAL_PRIMITIVES`` / ``PHASE_F_CONDITIONAL_PRIMITIVES``
@@ -24,7 +24,7 @@ Tier exclusion (mirrors ``BEHAVE-EXTRACTOR.md:180-223``):
 """
 from __future__ import annotations
 
-from decnet_behave_shell.spec.primitives import PRIMITIVE_REGISTRY
+from behave_shell.spec.primitives import PRIMITIVE_REGISTRY
 
 from tests.profiler.behave_shell.test_calibration_grid import (
     PHASE_ABCDEFG_PRIMITIVES,