palette tooltip: contextual description per lock state; earned date below Unlocked in green — TDD

- _palettes_for_user: shoptalk→description; "available by default" / "explore to unlock" / "recognized via {Title}"; unlocked_date key carries earned_at ISO for Note-unlocked
- template: data-shoptalk→data-description; data-unlocked-date now holds ISO datetime (was literal "Default")
- dashboard.js: lockText drops "— Default"; dateLine renders "Apr 22, 2026 · 3:05 AM" after Unlocked line
- _palette-picker.scss: tt-shoptalk→tt-description in display:block list; tt-date added
- _tooltips.scss: .tt-date mirrors .tt-expiry w. --priGn colour

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/static_src/scss/_palette-picker.scss

@@ -80,7 +80,8 @@
 #id_tooltip_portal {
     // Override .tt { display: none } — portal content is shown/hidden by JS
     .tt-title,
-    .tt-shoptalk,
+    .tt-description,
+    .tt-date,
     .tt-lock {
         display: block;
     }