Style: enforce official ktlint formatting and unify root .editorconfig

[calebareeveso]

What I added

• Added root .editorconfig: Enforces ktlint_code_style = ktlint_official and ignores function naming on @Composable functions across all projects.
• Configured Spotless & Removed Overrides: Pointed agent and ChatApp Gradle files directly to the root .editorconfig (setEditorConfigPath) and deleted localized subfolder overrides.
• Fixed Spotless Errors: Renamed BuiltInAppFunctions.kt to BaseBuiltInAppFunctionService.kt and FakeAppFunctions.kt to BaseFakeAppFunctionService.kt to match the class names brought in by pulling from upstream (1.0.0-alpha10). This is because ktlint_official throws a standard:filename Spotless build error when a file's name does not match the single class inside it.
• Updated README Documentation: Updated README.md under "Code Style" to explicitly clarify that Spotless must be run using individual subproject wrappers when executed from the repository root (./agent/gradlew -p agent spotlessApply && ./ChatApp/gradlew -p ChatApp spotlessApply).
• Applied Baseline Formatting: Ran spotlessApply across all modules (agent and ChatApp).

[gemini-code-assist]

Code Review

This pull request introduces a root-level .editorconfig file configured with the official ktlint code style and updates the Spotless configurations in both the ChatApp and agent build files to reference it. Consequently, various Kotlin source files, tests, and build scripts have been reformatted to comply with these styling rules, including adjustments to imports, line wrapping, and spacing. Additionally, the README.md has been updated with instructions on how to run Spotless formatting across the separate Gradle projects. There are no review comments, and I have no additional feedback to provide.

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