test(agent-runner): add dispatch, origin metadata, and thread resolution tests

Add 14 tests covering key routing and dispatch flows that previously had
zero direct coverage:

dispatchResultText:
- bare text produces no outbound (scratchpad only)
- unknown destination dropped, valid destination sent
- multiple <message> blocks each produce correct outbound
- internal tags stripped from scratchpad

originAttr / from= metadata:
- chat/task/webhook/system messages include from= when destination matches
- fallback to raw unknown:channel:platform when no match
- from= omitted when routing is null

resolveDestinationThread:
- null thread_id when no prior inbound from destination
- most recent thread_id wins with multiple inbound messages

Also fix merge issue: restore getAllDestinations import removed by our PR
but still needed by #2327's compaction reminder. Fix stale destinations
test assertion from #2328 ("no special wrapping needed" → "Every response
must be wrapped").

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

container/agent-runner/src/destinations.test.ts

@@ -33,14 +33,14 @@ describe('buildSystemPromptAddendum — multi-destination routing guidance', ()
     expect(prompt).toContain('`whatsapp-mg-17780`');
   });
 
-  it('omits the default-routing nudge for a single destination (short-circuited)', () => {
+  it('requires explicit wrapping even for a single destination', () => {
     seedDestination('casa', 'Casa', 'whatsapp', 'group-1@g.us');
 
     const prompt = buildSystemPromptAddendum('Casa');
 
-    // Single-destination path uses the simpler "no special wrapping needed" copy
-    expect(prompt).toContain('no special wrapping needed');
-    expect(prompt).not.toContain('Default routing');
+    expect(prompt).toContain('Every response must be wrapped');
+    expect(prompt).toContain('<message to="name">');
+    expect(prompt).toContain('`casa`');
   });
 
   it('handles the no-destination case without crashing', () => {
@@ -49,4 +49,15 @@ describe('buildSystemPromptAddendum — multi-destination routing guidance', ()
     expect(prompt).toContain('no configured destinations');
     expect(prompt).not.toContain('Default routing');
   });
+
+  it('includes default-routing and wrapping instructions for single destination', () => {
+    seedDestination('casa', 'Casa', 'whatsapp', 'group-1@g.us');
+
+    const prompt = buildSystemPromptAddendum('Casa');
+
+    expect(prompt).toContain('Every response must be wrapped');
+    expect(prompt).toContain('<message to="name">');
+    expect(prompt).toContain('Default routing');
+    expect(prompt).toContain('`casa`');
+  });
 });