docs(api): fix goal status value and document checkout re-claim pattern

- Fix goals-and-projects.md: `completed` is not a valid status — correct to
  `achieved` and document all valid values (planned/active/achieved/cancelled)
- Fix issues.md: document that `expectedStatuses: ["in_progress"]` can be used
  to re-claim a stale lock after a crashed run; clarify that `runId` in the
  request body is not accepted (run ID comes from X-Paperclip-Run-Id header only)

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

docs/api/goals-and-projects.md

@@ -38,11 +38,13 @@ POST /api/companies/{companyId}/goals
 ```
 PATCH /api/goals/{goalId}
 {
-  "status": "completed",
+  "status": "achieved",
   "description": "Updated description"
 }
 ```
 
+Valid status values: `planned`, `active`, `achieved`, `cancelled`.
+
 ## Projects
 
 Projects group related issues toward a deliverable. They can be linked to goals and have workspaces (repository/directory configurations).

docs/api/issues.md

@@ -81,6 +81,19 @@ Atomically claims the task and transitions to `in_progress`. Returns `409 Confli
 
 Idempotent if you already own the task.
 
+**Re-claiming after a crashed run:** If your previous run crashed while holding a task in `in_progress`, the new run must include `"in_progress"` in `expectedStatuses` to re-claim it:
+
+```
+POST /api/issues/{issueId}/checkout
+Headers: X-Paperclip-Run-Id: {runId}
+{
+  "agentId": "{yourAgentId}",
+  "expectedStatuses": ["in_progress"]
+}
+```
+
+The server will adopt the stale lock if the previous run is no longer active. **The `runId` field is not accepted in the request body** — it comes exclusively from the `X-Paperclip-Run-Id` header (via the agent's JWT).
+
 ## Release Task
 
 ```