feat(config): Restructure .taskmasterconfig and enhance gateway integration

Config Structure Changes and Gateway Integration

## Configuration Structure Changes
- Restructured .taskmasterconfig to use 'account' section for user settings
- Moved userId, userEmail, mode, telemetryEnabled from global to account section
- API keys remain isolated in .env file (not accessible to AI)
- Enhanced getUserId() to always return value, never null (sets default '1234567890')

## Gateway Integration Enhancements
- Updated registerUserWithGateway() to accept both email and userId parameters
- Enhanced /auth/init endpoint integration for existing user validation
- API key updates automatically written to .env during registration process
- Improved user identification and validation flow

## Code Updates for New Structure
- Fixed config-manager.js getter functions for account section access
- Updated user-management.js to use config.account.userId/mode
- Modified telemetry-submission.js to read from account section
- Added getTelemetryEnabled() function with proper account section access
- Enhanced telemetry configuration reading with new structure

## Comprehensive Test Updates
- Updated integration tests (init-config.test.js) for new config structure
- Fixed unit tests (config-manager.test.js) with updated default config
- Updated telemetry tests (telemetry-submission.test.js) for account structure
- Added missing getTelemetryEnabled mock to ai-services-unified.test.js
- Fixed all test expectations to use config.account.* instead of config.global.*
- Removed references to deprecated config.subscription object

## Configuration Access Consistency
- Standardized configuration access patterns across entire codebase
- Clean separation: user settings in account, API keys in .env, models/global in respective sections
- All tests passing with new configuration structure
- Maintained backward compatibility during transition

Changes support enhanced telemetry system with proper user management and gateway integration while maintaining security through API key isolation.

.cursor/rules/architecture.mdc

@@ -39,12 +39,12 @@ alwaysApply: false
     - **Responsibilities** (See also: [`ai_services.mdc`](mdc:.cursor/rules/ai_services.mdc)):
       - Exports `generateTextService`, `generateObjectService`.
       - Handles provider/model selection based on `role` and `.taskmasterconfig`.
-      - Resolves API keys (from `.env` or `session.env`).
+      - Resolves API keys (from `.env` or `session.env`). As the AI agent, you do not have access to read the .env -- but do not attempt to recreate it!
       - Implements fallback and retry logic.
       - Orchestrates calls to provider-specific implementations (`src/ai-providers/`).
     - Telemetry data generated by the AI service layer is propagated upwards through core logic, direct functions, and MCP tools. See [`telemetry.mdc`](mdc:.cursor/rules/telemetry.mdc) for the detailed integration pattern.
 
-  - **[`src/ai-providers/*.js`](mdc:src/ai-providers/): Provider-Specific Implementations**
+  - **[`src/ai-providers/*.js`](mdc:src/ai-providers): Provider-Specific Implementations**
     - **Purpose**: Provider-specific wrappers for Vercel AI SDK functions.
     - **Responsibilities**: Interact directly with Vercel AI SDK adapters.
 
@@ -63,7 +63,7 @@ alwaysApply: false
       - API Key Resolution (`resolveEnvVariable`).
       - Silent Mode Control (`enableSilentMode`, `disableSilentMode`).
 
-  - **[`mcp-server/`](mdc:mcp-server/): MCP Server Integration**
+  - **[`mcp-server/`](mdc:mcp-server): MCP Server Integration**
     - **Purpose**: Provides MCP interface using FastMCP.
     - **Responsibilities** (See also: [`mcp.mdc`](mdc:.cursor/rules/mcp.mdc)):
       - Registers tools (`mcp-server/src/tools/*.js`). Tool `execute` methods **should be wrapped** with the `withNormalizedProjectRoot` HOF (from `tools/utils.js`) to ensure consistent path handling.