Define intended purpose and control medical claims

[KeyffMS]

What changed

• record the intended users, environment, function and exclusions for SightAdapt 0.5.0.50-alpha;
• position the current product as general-purpose accessibility/display-personalization software without an intended medical purpose;
• prohibit diagnosis, treatment, therapy, clinical-effectiveness and named-condition claims;
• define approved terminology and a non-medical-purpose statement;
• record the repository, About, release, support, brand and external-surface review scope;
• require a new qualified EU medical-device regulatory assessment before medical targeting, clinical workflows or related claims;
• apply the policy to README, brand, release and store-description rules.

Scope

Documentation and claims governance only. Application behavior is unchanged. No professional classification opinion is claimed.

Closes #89.