refactor: rename Personal Pro to Skipper and Team Pro to Admiral (#256)

Align paid tier names with Sencho's nautical identity. Internal variant
values ('personal'/'team') remain unchanged in code, database, and
Lemon Squeezy integration — only user-facing display names updated.

- Backend: requireTeamPro → requireAdmiral, TEAM_PRO_REQUIRED → ADMIRAL_REQUIRED
- Frontend: TeamProGate.tsx → AdmiralGate.tsx, TierBadge labels updated
- Website: PricingSection tier names and nautical descriptions
- Docs: all 11 affected pages renamed, nautical footnote added to licensing

backend/src/services/LicenseService.ts

@@ -179,7 +179,7 @@ export class LicenseService {
 
     /**
      * Get the license variant (personal or team) from stored metadata.
-     * Trial licenses default to "personal" - Team Pro features require a Team Pro license.
+     * Trial licenses default to "personal" - Admiral features require an Admiral license.
      */
     public getVariant(): LicenseVariant {
         const db = DatabaseService.getInstance();