Update custom function invocation message to include class name

[xterao]

Fix the error message shown when a custom-function call is invalid. The doma.compile.
config content that specifies the function-definition class is cached and only refreshed when the file’s last-modified timestamp changes.

To help users verify that their updated settings have been picked up, include the referenced class name in the error message during code inspection.

[Copilot]

Pull Request Overview

This PR enhances the invalid custom-function error message to include the configured function-definition class name and adds documentation about config caching.

• Updated both English and Japanese message bundles to append a class-name placeholder
• Extended the validator result and visitor processor to pass the custom-function class into the error message
• Documented caching behavior in the README

Comments suppressed due to low confidence (3)

src/main/resources/messages/DomaToolsBundle_ja.properties:15

• The Japanese resource still contains the English phrase 'in class [{1}]'. Please replace this with a proper Japanese translation for consistency.

inspection.invalid.sql.notFound.customFunction=定義されていない組み込み関数またはカスタム関数が呼び出されています:[{0}] in class [{1}]

src/main/kotlin/org/domaframework/doma/intellij/common/sql/validator/result/ValidationInvalidFunctionCallResult.kt:29

• [nitpick] The parameter expressionClassName represents the custom-function class name; consider renaming it to customFunctionClassName for clarity and to match other identifiers.

private val expressionClassName: String,

src/main/kotlin/org/domaframework/doma/intellij/common/sql/validator/result/ValidationInvalidFunctionCallResult.kt:44

• There are currently no tests verifying that the error message includes the class name. Adding unit tests for ValidationInvalidFunctionCallResult#setHighlight would ensure this new behavior is covered.

expressionClassName,