fix(jira): correct browse URL, rename Procedure to Proof of Concept; feat(tempo): debug endpoint + UI

Jira URL fix:
- JiraLinkPanel now fetches the configured Jira base URL via getJiraConfig()
  instead of hardcoding https://jira.atlassian.com; falls back to the old
  value if config is not yet loaded

Description fix:
- _build_test_description: renamed 'h3. Procedure' -> 'h3. Proof of Concept'
  so the procedure/tool block maps to the correct Jira field label

Tempo debug:
- New POST /system/tempo-test endpoint: checks TEMPO_ENABLED, token,
  user jira_account_id, and makes a real API call; always returns HTTP 200
  with status field (Cloudflare-safe)
- docker-compose.prod.yml: added TEMPO_ENABLED, TEMPO_API_TOKEN,
  TEMPO_DEFAULT_WORK_TYPE env vars (default off, ready to enable)
- SettingsPage: added 'Test Tempo Connection' button in Jira admin tab
  with clear feedback showing what's missing

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

frontend/src/api/settings.ts

@@ -188,3 +188,12 @@ export async function testJiraConnection(): Promise<{
   return data;
 }
 
+export async function testTempoConnection(): Promise<{
+  status: "ok" | "error" | "disabled";
+  message?: string;
+  worklogs_found?: number | string;
+}> {
+  const { data } = await client.post("/system/tempo-test");
+  return data;
+}
+