rename: kafka → samsa

Full project rename from kafka to samsa (after Gregor Samsa, who
woke one morning from uneasy dreams to find himself transformed).

- Module: github.com/metamorphosis-dev/kafka → samsa
- Binary: cmd/kafka/ → cmd/samsa/
- CSS: kafka.css → samsa.css
- UI: all 'kafka' product names, titles, localStorage keys → samsa
- localStorage keys: kafka-theme → samsa-theme, kafka-engines → samsa-engines
- OpenSearch: ShortName, LongName, description, URLs updated
- AGPL headers: 'kafka' → 'samsa'
- Docs, configs, examples updated
- Cache key prefix: kafka: → samsa:

docs/superpowers/specs/2026-03-22-brave-search-frontend-redesign.md

@@ -2,7 +2,7 @@
 
 ## Overview
 
-Redesign the kafka frontend to match Brave Search's clean, functional aesthetic with emphasis on layout changes: three-column results page, category tiles on homepage, and a hybrid preferences system with full-page `/preferences` route.
+Redesign the samsa frontend to match Brave Search's clean, functional aesthetic with emphasis on layout changes: three-column results page, category tiles on homepage, and a hybrid preferences system with full-page `/preferences` route.
 
 ## Design Principles
 
@@ -302,7 +302,7 @@ On mobile (< 768px):
 | `internal/views/templates/results.html` | Add left sidebar, restructure for three columns |
 | `internal/views/templates/base.html` | Minimal changes (no structural changes needed) |
 | `internal/views/templates/preferences.html` | **New** — full preferences page |
-| `internal/views/static/css/kafka.css` | Add layout grids, category tiles, sidebar styles, sticky positioning, mobile breakpoints |
+| `internal/views/static/css/samsa.css` | Add layout grids, category tiles, sidebar styles, sticky positioning, mobile breakpoints |
 | `internal/views/static/js/settings.js` | Reduce popover to theme + engines; add preferences page JS |
 | `internal/httpapi/httpapi.go` | Add `/preferences` route (GET + POST) |
 | `internal/views/views.go` | Add preferences template rendering |