chore: release 1.0.6 and keep the live matrix out of the CI gate

The thinking matrix had been running inside make ci all along, which is
not what the design claimed. It takes seven minutes, spends 137 real
calls, and its criteria are statistical, so a network hiccup fails the
build for reasons unrelated to the change under test -- one run died on
three consecutive network errors exhausting the source.

The project already has the mechanism for this: the slow marker, which
addopts excludes by default and the config comments describe as "CI runs
it on demand". Marking the matrix slow brings make ci back down from
seven minutes to ninety seconds while the matrix stays a merge
requirement via -m slow.

The design also claimed e2e does not run in CI. It does: make test runs
pytest over tests/, e2e included, and the existing smoke tests really
call the gateway whenever .env has credentials. Only slow-marked tests
are excluded. Both documents now say so.

Version sources are pyproject and __init__; a test enforces they agree,
and it caught the second one being missed.

src/polygateway/__init__.py

@@ -31,7 +31,7 @@ from polygateway.types import (
     SourceConfig,
 )
 
-__version__ = "1.0.5"
+__version__ = "1.0.6"
 
 __all__ = [
     "DEFAULT_PROFILES",