feat: archive a project instead of deleting it

The owner archives a finished project (archiveProject, POST
/projects/{project}/archive) and brings it back (unarchive). While
archived it stays readable, managers still read its rules and webhooks,
but no command changes it: contributing and managing checks refuse with
422, votes and public proposals too, and automations do not run. The web
shows a read-only notice on every page of it (with «Desarchivar» for the
owner), hides what edits, marks it on the home page and lists it last.

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

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

@@ -128,6 +128,13 @@ export class ProjectDto {
   @ApiProperty({ type: ProjectSettingsDto })
   settings!: ProjectSettingsDto;
   @ApiProperty({ format: 'date-time' }) createdAt!: string;
+  @ApiProperty({
+    type: String,
+    nullable: true,
+    format: 'date-time',
+    description: 'Archived since then (read-only); null while active',
+  })
+  archivedAt!: string | null;
   @ApiProperty({ format: 'date-time' }) updatedAt!: string;
   @ApiProperty({ description: 'Version of the aggregate (event count)' })
   version!: number;

libs/api/tracker/presenters/src/lib/http/projects.controller.ts

@@ -5,6 +5,7 @@ import {
   Get,
   Param,
   Patch,
+  HttpCode,
   Post,
   Put,
   Query,
@@ -148,6 +149,38 @@ export class ProjectsController {
     );
   }
 
+  @Post(':project/archive')
+  @HttpCode(200)
+  @PROJECT
+  @ApiOperation({
+    summary: 'Archive a project (owner only)',
+    description:
+      'It stays readable (board, tickets, history, statistics); nothing can change until it is unarchived.',
+  })
+  @ApiOkResponse({ type: CommandResultDto })
+  @ApiCommandErrors()
+  async archive(@CurrentUser() me: User, @Param('project') project: string) {
+    return this.projects.setArchived(
+      me.id,
+      await this.refs.projectId(me.id, project),
+      true,
+    );
+  }
+
+  @Post(':project/unarchive')
+  @HttpCode(200)
+  @PROJECT
+  @ApiOperation({ summary: 'Bring an archived project back (owner only)' })
+  @ApiOkResponse({ type: CommandResultDto })
+  @ApiCommandErrors()
+  async unarchive(@CurrentUser() me: User, @Param('project') project: string) {
+    return this.projects.setArchived(
+      me.id,
+      await this.refs.projectId(me.id, project),
+      false,
+    );
+  }
+
   @Put(':project/settings')
   @PROJECT
   @ApiOperation({