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>

CAPABILITY-issue-tracking.yaml

@@ -1,8 +1,8 @@
-# Issue Facade Capability Manifest
+# Issue Core Capability Manifest
 # This file describes the capability to coding agents and integration systems
 
 metadata:
-  name: issue-facade
+  name: issue-core
   version: 1.0.0
   type: coordination-tool
   description: >
@@ -44,7 +44,7 @@ integration:
   methods:
     python_api:
       available: true
-      import: "from issue_tracker.backends.gitea import GiteaBackend"
+      import: "from issue_core.backends.gitea import GiteaBackend"
       docs: "AGENT_INTEGRATION.md"
 
     cli:
@@ -59,7 +59,7 @@ integration:
 
   installation:
     method: pip
-    command: "pip install -e capabilities/issue-facade/"
+    command: "pip install -e capabilities/issue-core/"
     verify: "issue --version"
 
   configuration:
@@ -119,8 +119,8 @@ credentials:
 
   security:
     - "Tokens never in code or logs"
-    - "Config stored in ~/.config/issue-facade/"
-    - "Per-repo config in .issue-facade/ (gitignored)"
+    - "Config stored in ~/.config/issue-core/"
+    - "Per-repo config in .issue-core/ (gitignored)"
 
   best_practices:
     - "Use read-only tokens for monitoring agents"
@@ -131,8 +131,8 @@ credentials:
 agent_guidance:
   quick_start: |
     # For Python agents:
-    from issue_tracker.backends.gitea import GiteaBackend
-    from issue_tracker.core.interfaces import IssueFilter
+    from issue_core.backends.gitea import GiteaBackend
+    from issue_core.core.interfaces import IssueFilter
 
     backend = GiteaBackend()
     backend.connect(config)
@@ -177,7 +177,7 @@ feedback:
     archived: "Resolved or outdated feedback"
 
   for_users: |
-    Submit feedback about issue-facade:
+    Submit feedback about issue-core:
       ./.capability/feedback submit "Feedback text"
       ./.capability/feedback submit detailed-feedback.md
 
@@ -261,7 +261,7 @@ support:
       solution: "Check GITEA_API_TOKEN is set and valid"
 
     - problem: "Command not found: issue"
-      solution: "Run: pip install -e capabilities/issue-facade/"
+      solution: "Run: pip install -e capabilities/issue-core/"
 
 # Integration priority score (higher = more important for agent to use)
 priority: