[#14312] Add more developer friendly schema validation error

[TobyCyan]

Part of #14312

Outline of Solution

• Add start-up error handler to retrieve and build the appropriate formatted error message with instructions.
• Stack trace preserved in terminal as logs.
• Gradle build will fail when an exception in thrown on start-up.

[Copilot]

Pull request overview

Adds a dev-server startup error handling layer to surface developer-friendly, actionable messages (currently focused on Hibernate schema validation failures) while integrating into the Jetty startup path.

Changes:

• Introduces StartupErrorHandler + factory/dispatcher to detect known startup exceptions and format guidance (e.g., ./gradlew liquibaseUpdate).
• Adds a SchemaValidationStartupErrorHandler to recognize schema validation failures and build a structured message.
• Wraps Jetty server.start() in Application to intercept startup failures and throw a dev-friendly exception; adds component tests for the new behavior.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/main/java/teammates/main/Application.java	Catches Jetty startup exceptions and routes them through the new dev startup error handler.
src/main/java/teammates/ui/errorhandlers/StartupErrorHandler.java	Defines the contract for formatting startup errors into dev-friendly messages.
src/main/java/teammates/ui/errorhandlers/SchemaValidationStartupErrorHandler.java	Implements schema-validation failure detection and message formatting.
src/main/java/teammates/ui/errorhandlers/DevServerStartupErrorHandlerFactory.java	Maps startup exceptions to the first matching handler (via reflection).
src/main/java/teammates/ui/errorhandlers/DevServerStartupErrorHandler.java	Throws a dev-friendly exception when a handler matches.
src/main/java/teammates/ui/errorhandlers/package-info.java	Adds package-level documentation for startup error handlers.
src/main/java/teammates/ui/exception/DevServerStartupException.java	Adds a dedicated runtime exception type for dev-server startup failures.
src/test/resources/testng-component.xml	Includes the new UI startup error handler tests in component test suite.
src/test/java/teammates/ui/devserverstartuperrorhandlers/*	Adds tests for handler detection, factory selection, and formatted message output.

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