fix: address PR review feedback (round 8)

- Fix inconsistent error code in set_collective_emoji (400 → -32603)
- Allow clearing emoji via set_collective_emoji(emoji=None)
- Remove destructiveHint from trash operations (soft deletes are recoverable)
- Change delete_collective to idempotentHint=False (requires trash precondition)
- Add restore_collective and get_trashed_collectives tools
- Add unit tests for ValueError guard, clear-emoji path, and new tools
- Add integration test for full trash/restore/delete lifecycle
- Verify move_page returns new title in response message

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

tests/server/test_annotations.py

@@ -78,8 +78,12 @@ async def test_delete_operations_are_idempotent(nc_mcp_client: ClientSession):
     """Verify delete operations are marked as idempotent (ADR-017 decision)."""
     tools = await nc_mcp_client.list_tools()
 
+    # Exceptions: delete operations that require a precondition (e.g. must be
+    # trashed first), so calling twice produces an error on the second call.
+    non_idempotent_deletes = {"collectives_delete_collective"}
+
     for tool in tools.tools:
-        if "delete" in tool.name.lower():
+        if "delete" in tool.name.lower() and tool.name not in non_idempotent_deletes:
             assert tool.annotations is not None, f"Tool {tool.name} missing annotations"
             assert tool.annotations.idempotentHint is True, (
                 f"Delete tool {tool.name} should be idempotent (same end state)"