feat(auth): role-based permissions + user management (plan phase 1)

Adds the RBAC foundation the CRUD phases build on, and the first write
module (users). The platform was read-only: every controller was guarded
only by AuthenticatedGuard and UserRole was ADMIN|STAFF. The old PHP app
stored level+role but enforced neither, so this is a fresh design.

Permission model (server-authoritative):
- UserRole expanded to an ordered rank ADMIN > MANAGER > STAFF > VIEWER.
  VIEWER is the read-only role; STAFF+ can write.
- auth/abilities.ts: ROLE_RANK + ABILITY_MIN matrix + can()/abilitiesFor().
- @RequireAbility decorator + AbilityGuard enforce it on write routes;
  reads stay on AuthenticatedGuard so any logged-in user can read.
- /auth/login and /auth/me now return the resolved abilities map, so the
  web gates its UI off one payload instead of duplicating the rules.

User management (ADMIN-only, ability "user:manage"):
- UsersService gains list/create/update/resetPassword (argon2), never
  returns passwordHash; blocks self-deactivation and self-demotion;
  maps duplicate email to 409.
- UsersController: GET/POST /users, PATCH /users/:id,
  POST /users/:id/reset-password.
- Every mutation logged via new AuditService over the existing
  ActivityLog model (global CommonModule).

Web:
- AuthContext + useAuth/useCan; AppShell provides the user and gates the
  new "Usuarios" nav entry on user:manage; shows the user's role.
- /usuarios admin page: list + create/edit form + password reset +
  active toggle, Spanish-first, reusing existing card/table/field styles.

Schema pushed to dev (enum only, non-destructive). Verified end-to-end
against dev: admin CRUD works, VIEWER writes 403 while reads 200,
self-lockout guards and duplicate-email 409 all hold.

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

apps/api/src/users/users.controller.ts

@@ -0,0 +1,72 @@
+import {
+  Body,
+  Controller,
+  Get,
+  Param,
+  Patch,
+  Post,
+  Req,
+  UseGuards,
+} from "@nestjs/common";
+import { Request } from "express";
+import { AuthenticatedGuard } from "../auth/authenticated.guard";
+import { AbilityGuard } from "../auth/ability.guard";
+import { RequireAbility } from "../auth/require-ability.decorator";
+import { AuditService } from "../common/audit.service";
+import { UsersService } from "./users.service";
+import { CreateUserDto } from "./create-user.dto";
+import { UpdateUserDto } from "./update-user.dto";
+import { ResetPasswordDto } from "./reset-password.dto";
+
+/** Every route here is ADMIN-only (ability "user:manage"). */
+@UseGuards(AuthenticatedGuard, AbilityGuard)
+@RequireAbility("user:manage")
+@Controller("users")
+export class UsersController {
+  constructor(
+    private readonly users: UsersService,
+    private readonly audit: AuditService,
+  ) {}
+
+  private actingId(req: Request): string {
+    return (req.user as { id: string }).id;
+  }
+
+  @Get()
+  list() {
+    return this.users.list();
+  }
+
+  @Post()
+  async create(@Body() dto: CreateUserDto, @Req() req: Request) {
+    const user = await this.users.create(dto);
+    void this.audit.log(this.actingId(req), "user.create", {
+      userId: user.id,
+      email: user.email,
+      role: user.role,
+    });
+    return user;
+  }
+
+  @Patch(":id")
+  async update(
+    @Param("id") id: string,
+    @Body() dto: UpdateUserDto,
+    @Req() req: Request,
+  ) {
+    const user = await this.users.update(id, dto, this.actingId(req));
+    void this.audit.log(this.actingId(req), "user.update", { userId: id, changes: dto });
+    return user;
+  }
+
+  @Post(":id/reset-password")
+  async resetPassword(
+    @Param("id") id: string,
+    @Body() dto: ResetPasswordDto,
+    @Req() req: Request,
+  ) {
+    const user = await this.users.resetPassword(id, dto.password);
+    void this.audit.log(this.actingId(req), "user.reset_password", { userId: id });
+    return user;
+  }
+}