[Feature Request] Ability to change account email address to prevent workspace data loss - OpenAI/Codex added this feature already

### Description
There is currently no mechanism within the Claude platform settings to change or update a user's primary account email address.

### Context & Impact
While competing platforms like ChatGPT (OpenAI) have natively introduced this capability, Claude accounts remain permanently locked to their initial creation email.

For developers and power users who have invested hundreds of hours building out specific Claude instances, custom tool structures, and long-term project contexts, this creates a severe single point of failure.

If a user loses access to their underlying corporate domain (due to corporate restructuring, domain migration, or business closure), they are entirely cut off from their development history and assets with no migration path available.

### Proposed Solution
Implement a secure email modification workflow within the standard User Settings panel:
1. Allow the user to input a new destination email.
2. Send a time-sensitive verification link to both the old and new email addresses to prevent hijacking.
3. Successfully transfer all account contexts, billing history, and project assets to the updated identifier.