feat: comments marked as decisions, on top of the ticket and searchable

Whoever can change the ticket flags a comment as a decision (new event
CommentDecisionMarkedEvent on the comment). The ticket page lists its
decisions above the description, with a link to the comment in the
conversation (`?comment=<id>` scrolls to it and points at it), and the
search palette finds them by their text across my projects.

API: markDecision / PUT-DELETE /api/comments/{id}/decision; Issue.decisions
and GET /api/issues/{issue}/decisions; decisions(projectId?, search) and
GET /api/projects/{project}/decisions, GET /api/me/decisions. MCP:
mark_decision, search_decisions, and get_issue includes them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/api/tracker/presenters/src/lib/http/dto/requests.dto.ts

@@ -501,6 +501,22 @@ export class PageQueryDto {
   offset = 0;
 }
 
+export class DecisionsQueryDto {
+  @ApiPropertyOptional({ description: 'Words in the decision' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(200)
+  search?: string;
+
+  @ApiPropertyOptional({ type: Number, default: 20, minimum: 1, maximum: 100 })
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  @Max(100)
+  limit = 20;
+}
+
 // ---- Issues -----------------------------------------------------------------
 
 export class MyIssuesQueryDto extends PageQueryDto {