[Feature] Make the campus assistant example a richer multi-tool tutorial

Feature Request

Enhance the campus assistant example in spring-ai-alibaba-tool-calling-example so it better demonstrates multi-tool composition, local tool validation, and weather-aware activity planning.

Is your feature request related to a problem? Please describe

The merged campus assistant example already demonstrates basic composition of TimeTools, WeatherService, and a local schedule tool. However, the local tool currently returns a relatively concise result and the example can be more useful as a tutorial if it demonstrates multiple local @Tool methods, parameter validation, and weather-aware risk estimation without introducing new external services.

Describe the solution you'd like

I would like to enhance the existing example by:

1. Expanding CampusScheduleTools#createCampusSchedule into a staged campus plan with preparation, main activity, and wrap-up time.
2. Adding a second local tool method estimateCampusActivityRisk to estimate outdoor activity risk from weather summary, activity, and duration.
3. Adding validation for blank activity, blank start time, blank weather summary, and invalid duration.
4. Adding more HTTP examples for weather-aware campus activities and indoor backup scenarios.
5. Increasing local unit test coverage from 3 cases to 9 cases.

The change stays inside the existing Tool Calling example module and does not introduce new external services.

Describe alternatives you've considered

I considered adding a larger agent workflow or map-based route planning, but those would introduce a wider review surface and additional API keys. A focused enhancement to the existing campus assistant example keeps the PR reviewable while still making the tutorial more substantial.

Additional context

This is a follow-up to the merged campus assistant PR: https://github.com/spring-ai-alibaba/examples/pull/463

Local verification has passed:

mvn -f spring-ai-alibaba-tool-calling-example/pom.xml test
Tests run: 9, Failures: 0, Errors: 0, Skipped: 0
BUILD SUCCESS