Add unit test suite for mission module BT nodes

[Copilot]

The mission module had no test coverage despite supporting automatic task orchestration via behavior trees. This adds a closed-loop test suite that validates all BT node state transitions using a virtual blackboard and MissionContext mock injection — no CyberRT or hardware required.

New: modules/mission/mission_test.cc

• BtTypeConvertersTest — PointENU string conversion: "x,y", "x,y,z", and invalid input (throws)
• CheckBatteryNodeTest — FAILURE with null chassis, SUCCESS/FAILURE against threshold
• StationWaitNodeTest — RUNNING on first tick, SUCCESS after deadline passes
• MoveToNodeTest — RUNNING without localization, SUCCESS within 3 m, RUNNING when distant
• ChargeNodeTest — RUNNING without chassis, SUCCESS when SOC ≥ target
• BtFactoryIntegrationTest — inline XML tree loading; patrol task stays RUNNING, shuttle bus short-circuits to FAILURE on low battery

// Virtual blackboard pre-populated with waypoints; MissionContext injected with mock data
auto chassis = std::make_shared<apollo::canbus::Chassis>();
chassis->set_battery_soc_percentage(5.0);
MissionContext::Instance()->UpdateChassis(chassis);

// CheckBattery(min=20) fails → whole Sequence fails immediately
BT::NodeStatus status = tree.tickOnce();
EXPECT_EQ(status, BT::NodeStatus::FAILURE);

Modified: modules/mission/BUILD

Added cc_test target mission_test with deps on node libraries, proto messages, behaviortree_cpp, and gtest_main.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Feature]: Test mission module</issue_title>
<issue_description>### Use Case / Motivation

Currently, mission mode supports automatic task orchestration, but we haven't provided a minimum example.

https://github.com/wheelos/apollo-lite/tree/main/modules/mission/conf

Proposed Implementation

No response

Alternatives Considered

No response</issue_description>

<agent_instructions>## 1. System Design

Goal:
Build a “closed-loop” test environment that can simulate executor feedback and verify behavior status transitions.

Components:

• Test Runner:
  Loads behavior tree definitions from XML/YAML under bt_trees.

• Black-box Mock Layer:
  Simulates external inputs required by Action Nodes and Condition Nodes (e.g., sensor data, vehicle states).

• State Monitor:
  Subscribes to BT status updates and records node return values (SUCCESS, FAILURE, RUNNING).

• Assertion Engine:
  Checks whether the resulting behavior sequence matches expected outcomes.

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2. Review of Existing Design

In the modules/mission architecture:

• Supported: Yes — the existing framework typically includes a BT engine (e.g., Groot or BehaviorTree.CPP), and BT uses a Blackboard shared memory for key/value state communication. ([Cnblogs][1])

• Bottleneck:
  Current implementation may be tightly coupled with CyberRT or real hardware interfaces, making it hard to run in a test environment without physical systems.

• Improvements:
  Introduce a Virtual Blackboard that you can pre-populate with test data before execution, and use Mock Action nodes to replace real control commands.

</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature]: Test mission module #171

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