feat(capability-requests): add routing dispute & reroute workflow (CUST-WP-0027)

Adds a structured dispute mechanism when capability request routing is wrong:
- New `routing_disputed` status with four DB columns (dispute_reason, disputed_by,
  dispute_suggested_domain, disputed_at) via Alembic migration m0h1i2j3k4l5
- POST /capability-requests/{id}/dispute — any party can flag misrouting with a reason
  and optional suggested domain; notifies custodian + current fulfilling domain
- POST /capability-requests/{id}/reroute — custodian re-routes to correct domain via
  catalog_entry_id or direct slug; appends audit trail to routing_note; resets to requested
- Two new MCP tools: dispute_capability_routing and reroute_capability_request
- Dashboard: amber disputed-banner at top of Summary, routing_disputed Kanban column,
  dispute details (reason, suggested domain, raised-by) shown on disputed cards

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

workplans/CUST-WP-0027-capability-request-dispute.md

@@ -4,7 +4,7 @@ type: workplan
 title: "Capability Request Dispute & Negotiation"
 domain: custodian
 repo: the-custodian
-status: active
+status: done
 owner: custodian
 topic_slug: custodian
 created: "2026-03-21"
@@ -101,7 +101,7 @@ _VALID_TRANSITIONS = {
 
 ```task
 id: CUST-WP-0027-T01
-status: todo
+status: done
 priority: high
 state_hub_task_id: "41357812-9791-488d-883b-75cb07ae4c90"
 ```
@@ -123,7 +123,7 @@ Gate: `make migrate` runs cleanly; `make test` passes.
 
 ```task
 id: CUST-WP-0027-T02
-status: todo
+status: done
 priority: high
 state_hub_task_id: "39429f29-cf3a-440c-aca7-5b9e3b31b2d0"
 ```
@@ -145,7 +145,7 @@ fulfilling domain receive notifications.
 
 ```task
 id: CUST-WP-0027-T03
-status: todo
+status: done
 priority: high
 state_hub_task_id: "94ede349-ddd1-4572-bb18-43cb2e67326b"
 ```
@@ -168,7 +168,7 @@ Gate: full dispute→reroute→accept round-trip passes in tests.
 
 ```task
 id: CUST-WP-0027-T04
-status: todo
+status: done
 priority: medium
 state_hub_task_id: "e8d1e24e-8ec7-4c4a-b2b5-f6072ab7582c"
 ```
@@ -192,7 +192,7 @@ pattern (route → dispute → reroute → accept).
 
 ```task
 id: CUST-WP-0027-T05
-status: todo
+status: done
 priority: low
 state_hub_task_id: "a40b6a57-2cfd-4e09-ac00-3d4d2920eb7a"
 ```