refactor(tasks): Align update-tasks with unified AI service and remove obsolete helpers

Completes the refactoring of the AI-interacting task management functions by aligning `update-tasks.js` with the unified service architecture and removing now-unused helper files.

Key Changes:

- **`update-tasks.js` Refactoring:**

    - Replaced direct AI client calls and AI-specific config fetching with a call to `generateTextService` from `ai-services-unified.js`.

    - Preserved the original system and user prompts requesting a JSON array output.

    - Implemented manual JSON parsing (`parseUpdatedTasksFromText`) with Zod validation to handle the text response reliably.

    - Updated the core function signature to accept the standard `context` object (`{ session, mcpLog }`).

    - Corrected logger implementation to handle both MCP (`mcpLog`) and CLI (`consoleLog`) contexts appropriately.

- **Related Component Updates:**

    - Refactored `mcp-server/src/core/direct-functions/update-tasks.js` to use the standard direct function pattern (logger wrapper, silent mode, call core function with context).

    - Verified `mcp-server/src/tools/update.js` correctly passes arguments and context.

    - Verified `scripts/modules/commands.js` (update command) correctly calls the refactored core function.

- **Obsolete File Cleanup:**

    - Removed the now-unused `scripts/modules/task-manager/get-subtasks-from-ai.js` file and its export, as its functionality was integrated into `expand-task.js`.

    - Removed the now-unused `scripts/modules/task-manager/generate-subtask-prompt.js` file and its export for the same reason.

- **Task Management:**

    - Marked subtasks 61.38, 61.39, and 61.41 as complete.

This commit finalizes the alignment of `updateTasks`, `updateTaskById`, `expandTask`, `expandAllTasks`, `analyzeTaskComplexity`, `addTask`, and `parsePRD` with the unified AI service and configuration management patterns.

scripts/modules/commands.js

@@ -211,7 +211,7 @@ function registerCommands(programInstance) {
 		)
 		.action(async (options) => {
 			const tasksPath = options.file;
-			const fromId = parseInt(options.from, 10);
+			const fromId = parseInt(options.from, 10); // Validation happens here
 			const prompt = options.prompt;
 			const useResearch = options.research || false;
 
@@ -260,7 +260,14 @@ function registerCommands(programInstance) {
 				);
 			}
 
-			await updateTasks(tasksPath, fromId, prompt, useResearch);
+			// Call core updateTasks, passing empty context for CLI
+			await updateTasks(
+				tasksPath,
+				fromId,
+				prompt,
+				useResearch,
+				{} // Pass empty context
+			);
 		});
 
 	// update-task command