Align backend with frontend, make clips end-to-end, polish admin

Backend
- Add ClipSubmission entity + table (runtime bootstrapper) and
  POST /api/public/clips (server-derives platform from the link)
- Surface clip submissions in the admin season detail
- Add DELETE candidate/category/clip endpoints with audit entries

Frontend
- Clips admin: real moderation view (list, open link, delete) instead
  of placeholder; wired clipSubmissions through types/api/store
- Categories admin: add delete with confirm modal (matches Candidates)
- Voting ranking bar uses the unified purple gradient
- Fix ASCII transliterations to proper German umlauts across admin
- Remove orphan AdminView 2.vue

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Backend/Data/OperationalTablesBootstrapper.cs

@@ -49,5 +49,22 @@ public static class OperationalTablesBootstrapper
 
             CREATE INDEX IF NOT EXISTS "IX_AdminAuditEntries_CreatedAt"
             ON "AdminAuditEntries" ("CreatedAt" DESC);
+
+            CREATE TABLE IF NOT EXISTS "ClipSubmissions" (
+                "Id" integer GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+                "SeasonId" integer NOT NULL,
+                "CategoryId" integer NULL,
+                "SubmittedByTwitchId" character varying(120) NOT NULL,
+                "ClipUrl" character varying(500) NOT NULL,
+                "Title" character varying(200) NOT NULL,
+                "Creator" character varying(120) NOT NULL,
+                "Platform" character varying(40) NOT NULL,
+                "Status" character varying(20) NOT NULL,
+                "CreatedFromIp" character varying(80) NOT NULL,
+                "CreatedAt" timestamp with time zone NOT NULL
+            );
+
+            CREATE INDEX IF NOT EXISTS "IX_ClipSubmissions_SeasonId_Status"
+            ON "ClipSubmissions" ("SeasonId", "Status");
             """);
 }