Fix local development console errors

[areibman]

📥 Pull Request

📘 Description
This PR addresses excessive console errors and noise in local development mode by:

• Disabling PostHog initialization unless a key is present and the environment is not development or local.
• Adding checks to PostHogUserIdentifier to only interact with PostHog if it's loaded.
• Skipping /opsboard/users/me API calls when no session_id cookie is present in both useUser and the sign-in form.
• Reducing console logging for expected 401/403 authentication errors in non-production environments.

These changes prevent unnecessary network requests and console spam (e.g., 401/404 errors, JSON MIME errors) when working locally without a fully configured backend or analytics.

🧪 Testing
I ran the application locally and verified the following:

• PostHog-related 401/404 errors and JSON MIME errors are no longer present in the console.
• /opsboard/users/me calls are not made when no session_id cookie exists.
• Expected 401/403 API errors are now logged as warnings or suppressed in local mode, rather than noisy console errors.
• Authentication and user fetching still function correctly when a valid session is present.

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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