feat: rename to issue-core and add task ingestion endpoint

Renames the package, distribution, CLI alias, Makefile targets, and
working directory from issue-facade to issue-core, signalling its
role as the authoritative task lifecycle manager for the Coulomb org
(peer to activity-core, rules-core, project-core).

Adds POST /issues/ ingestion endpoint for activity-core's IssueSink,
under a new optional [api] extra. The endpoint is served by `issue
serve`, authenticates via the ISSUE_CORE_API_KEY env var (Bearer or
X-API-Key header), and routes the TaskSpec payload to the configured
default backend with full traceability metadata embedded in
sync_metadata.

- T01: Python package issue_tracker -> issue_core, dir rename
- T02: registered in state hub under custodian domain
- T03: INTENT.md (what it is, what it isn't, how it fits)
- T04: SCOPE.md (in/out-of-scope, integration boundaries)
- T05: POST /issues/ via FastAPI + Uvicorn, 9 unit tests
- T06: docs/nats-task-ingestion.md design stub

Closes ISSC-WP-0001.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workplans/ISSC-WP-0001-rename-and-task-ingestion.md

@@ -2,34 +2,34 @@
 id: ISSC-WP-0001
 type: workplan
 domain: custodian
-repo: issue-facade
-status: active
+repo: issue-core
+status: done
 state_hub_workstream_id: 1135fc1d-1f46-4e35-886d-04cc3b8050b6
 tasks:
   - id: T01
     title: Rename package issue-facade → issue-core throughout
     state_hub_task_id: b7054428-82a9-4d81-bfa8-5b5ee2eaf69f
-    status: todo
+    status: done
   - id: T02
     title: Register issue-core in state hub under capabilities domain
     state_hub_task_id: b1d36996-44ff-48b9-b208-709d6874453c
-    status: todo
+    status: done
   - id: T03
     title: Write INTENT.md
     state_hub_task_id: 265c6338-0310-409d-a081-6446042f6274
-    status: todo
+    status: done
   - id: T04
     title: Update or write SCOPE.md
     state_hub_task_id: f95ac730-7ba0-4eae-bcae-de1e7d24b164
-    status: todo
+    status: done
   - id: T05
     title: Implement task ingestion REST endpoint POST /issues/
     state_hub_task_id: 26af07e4-c072-42ad-bb5c-facb196156c9
-    status: todo
+    status: done
   - id: T06
     title: Document NATS subscriber interface (design stub)
     state_hub_task_id: dff61fed-1e8c-4eb3-bbd6-1e3742329945
-    status: todo
+    status: done
 created: "2026-05-14"
 ---