feat(models): implement custom model support for ollama/openrouter

Adds the ability for users to specify custom model IDs for Ollama and OpenRouter providers, bypassing the internal supported model list.

    - Introduces --ollama and --openrouter flags for the 'task-master models --set-<role>' command.
    - Updates the interactive 'task-master models --setup' to include options for entering custom Ollama/OpenRouter IDs.
    - Implements live validation against the OpenRouter API when a custom OpenRouter ID is provided.
    - Refines the model setting logic to prioritize explicit provider flags/choices.
    - Adds warnings when custom models are set.
    - Updates the changeset file.

scripts/modules/ui.js

@@ -2007,6 +2007,10 @@ function displayAvailableModels(availableModels) {
 				'\n' +
 				chalk.cyan(
 					`4. Run interactive setup: ${chalk.yellow('task-master models --setup')}`
+				) +
+				'\n' +
+				chalk.cyan(
+					`5. Use custom models: ${chalk.yellow('task-master models --custom --set-main|research|fallback <model_id>')}`
 				),
 			{
 				padding: 1,