feat: email notification for opportunity workspace

[jjenscodee]

Sends email notifications when LLMO strategy or opportunity statuses change via PUT /sites/{siteId}/llmo/strategy.
Changes:

• Templates: Uses llmo_opportunity_status_update and llmo_strategy_update (via EMAIL_LLMO_OPPORTUNITY_STATUS_UPDATE_TEMPLATE and EMAIL_LLMO_STRATEGY_UPDATE_TEMPLATE).
• Opportunity updates: Notifies assignee and strategy owner. Payload includes recipient_name, assignee_, strategy_owner_, opportunity_name, opportunity_status, strategy_url.
• Strategy updates: Notifies strategy owner and all opportunity assignees. Payload includes recipient_name, strategy_status, strategy_url, strategy_owner_*, opportunity_list.
• Name resolution: Uses TrialUser.findByEmailId for display names; falls back to email if not found.
• Missing strategy owner: Skips sending to owner when createdBy is missing; still sends to assignees.
• Strategy URL: Built from Site.getBaseURL() as https://llmo.now/{hostname}/insights/opportunity-workspace.
• Files: opportunity-workspace-notifications.js, email-service.js, llmo.js controller, tests, docs.

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