Rename package, CLI, and deploy artifacts to rein-aharness (HARNESS-WP-0002-T02)

agent_harness -> rein_aharness (package + all imports), CLI command
agent-harness -> rein-aharness, Docker image tag, k8s namespace/labels/
names, Makefile targets, deploy script env var/paths. In-repo identity
strings (hub event source, metrics harness field, default assignee,
argparse prog name, commit author identity) updated to match.

Historical documents left untouched on purpose: docs/adr/ADR-001-agent-harness-architecture.md,
docs/architecture.md (dated v0.1 snapshot), workplans/HARNESS-WP-0001
(completed under the old name), and the SSH host alias
"forgejo-agent-harness" (external ~/.ssh/config entry, not owned here).

Verified: 47/47 tests pass, CLI runs correctly from a fresh venv,
`make image` builds and the resulting container runs correctly.

deploy/README.md gained an explicit rename cutover checklist for what
this session cannot safely do unattended -- moving the host-side
secrets dir and checkout on railiance01, and not deleting the old k8s
namespace until the new one is confirmed working. The actual live
cutover (running that checklist against the real Railiance deployment)
is not attempted here -- real production surgery on binky-control's
live automation, needs the operator present.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

scripts/tenant_onboard_runs.py

@@ -19,8 +19,8 @@ _ROOT = Path(__file__).resolve().parents[1]
 if str(_ROOT) not in sys.path:
     sys.path.insert(0, str(_ROOT))
 
-from agent_harness.runner import run_task
-from agent_harness.taskspec import TaskSpec
+from rein_aharness.runner import run_task
+from rein_aharness.taskspec import TaskSpec
 
 
 class EvidenceAdapter:
@@ -47,9 +47,9 @@ class EvidenceAdapter:
             [
                 "git",
                 "-c",
-                "user.email=agent-harness@local",
+                "user.email=rein-aharness@local",
                 "-c",
-                "user.name=agent-harness",
+                "user.name=rein-aharness",
                 "commit",
                 "-qm",
                 f"harness onboard: {self.slug}",