fix(honcho): isolate session routing for multi-user gateway (#1500)

Salvaged from PR #1470 by adavyas.

Core fix: Honcho tool calls in a multi-session gateway could route to
the wrong session because honcho_tools.py relied on process-global
state. Now threads session context through the call chain:
  AIAgent._invoke_tool() → handle_function_call() → registry.dispatch()
  → handler **kw → _resolve_session_context()

Changes:
- Add _resolve_session_context() to prefer per-call context over globals
- Plumb honcho_manager + honcho_session_key through handle_function_call
- Add sync_honcho=False to run_conversation() for synthetic flush turns
- Pass honcho_session_key through gateway memory flush lifecycle
- Harden gateway PID detection when /proc cmdline is unreadable
- Make interrupt test scripts import-safe for pytest-xdist
- Wrap BibTeX examples in Jekyll raw blocks for docs build
- Fix thread-order-dependent assertion in client lifecycle test
- Expand Honcho docs: session isolation, lifecycle, routing internals

Dropped from original PR:
- Indentation change in _create_request_openai_client that would move
  client creation inside the lock (causes unnecessary contention)

Co-authored-by: adavyas <adavyas@users.noreply.github.com>

tests/gateway/test_resume_command.py

@@ -199,3 +199,28 @@ class TestHandleResumeCommand:
 
         assert real_key not in runner._running_agents
         db.close()
+
+    @pytest.mark.asyncio
+    async def test_resume_flushes_memories_with_gateway_session_key(self, tmp_path):
+        """Resume should preserve the gateway session key for Honcho flushes."""
+        from hermes_state import SessionDB
+
+        db = SessionDB(db_path=tmp_path / "state.db")
+        db.create_session("old_session", "telegram")
+        db.set_session_title("old_session", "Old Work")
+        db.create_session("current_session_001", "telegram")
+
+        event = _make_event(text="/resume Old Work")
+        runner = _make_runner(
+            session_db=db,
+            current_session_id="current_session_001",
+            event=event,
+        )
+
+        await runner._handle_resume_command(event)
+
+        runner._async_flush_memories.assert_called_once_with(
+            "current_session_001",
+            _session_key_for_event(event),
+        )
+        db.close()