refactor(twenty-server): consolidate AI tool provider architecture (#16355)

## Summary

Consolidates the AI tool provider architecture by creating a single
`ToolProviderService` as the entry point for all tool generation. This
removes multiple intermediate services and simplifies the codebase.

## Changes

### New Architecture
- **`ToolProviderService`**: Single service for all tool generation
with:
  - `getTools(spec)` - Get tools by category with permissions
  - `getToolByType(type)` - Get specific tool for workflow execution
  
- **`ToolCategory` enum**: Declarative specification of tool types:
  - `DATABASE_CRUD` - Record CRUD operations
  - `ACTION` - HTTP requests, email sending, article search
  - `WORKFLOW` - Workflow management tools
  - `METADATA` - Object/field metadata tools
  - `NATIVE_MODEL` - Model-specific tools (e.g., web search)

- **`ToolSpecification` type**: Clean API for requesting tools with
permissions

### Removed
- `AiToolsModule` - No longer needed
- `ToolService` - Logic inlined into ToolProviderService
- `ToolAdapterService` - Logic inlined into ToolProviderService
- `ToolRegistryService` - Logic inlined into ToolProviderService

### Updated
- All consumers (agents, chat, MCP, workflows) now use
`ToolProviderService`
- Test files updated accordingly

## Stats
- **547 insertions, 1146 deletions** (net ~600 lines removed)
- 4 services deleted
- 1 module deleted

## Testing
- [x] Typecheck passes
- [x] Lint passes

packages/twenty-server/src/engine/core-modules/billing/billing.module.ts

@@ -35,7 +35,6 @@ import { UserWorkspaceEntity } from 'src/engine/core-modules/user-workspace/user
 import { WorkspaceEntity } from 'src/engine/core-modules/workspace/workspace.entity';
 import { AiBillingModule } from 'src/engine/metadata-modules/ai/ai-billing/ai-billing.module';
 import { AiModelsModule } from 'src/engine/metadata-modules/ai/ai-models/ai-models.module';
-import { AiToolsModule } from 'src/engine/metadata-modules/ai/ai-tools/ai-tools.module';
 import { DataSourceModule } from 'src/engine/metadata-modules/data-source/data-source.module';
 import { PermissionsModule } from 'src/engine/metadata-modules/permissions/permissions.module';
 
@@ -47,7 +46,6 @@ import { PermissionsModule } from 'src/engine/metadata-modules/permissions/permi
     PermissionsModule,
     AiBillingModule,
     AiModelsModule,
-    AiToolsModule,
     WorkspaceDomainsModule,
     TypeOrmModule.forFeature([
       BillingSubscriptionEntity,