feat: add public read-only sharing for computers

Adds the ability for an owner to share a computer build via a public,
unauthenticated link, inspired by a feature request from the original
pcbuilder repo (no such feature actually existed there — implemented
from scratch here).

- New columns on computers: share_token (unique, nullable), share_enabled,
  share_show_sell_price, share_show_cost
- computer_share_service.ts: generates a non-guessable share token
  (crypto.randomBytes, base64url), enables/disables sharing, and supports
  rotating the token to invalidate previously distributed links
- ComputerShareController (authenticated, owner-scoped like the rest of
  the app): PUT /computers/:id/share to update settings, POST
  /computers/:id/share/rotate to rotate the token
- PublicComputerController + GET /share/:token (outside any auth/guest
  group, reachable anonymously): resolves only computers with
  share_enabled = true, 404 otherwise
- ComputerPublicTransformer: dedicated read-only projection that never
  leaks userId, and only includes sellPrice/cost when the owner opted in
  via share_show_sell_price / share_show_cost — everything else (title,
  scores, state, components, pictures) is always visible on a shared link
- ComputerShareModal.vue: owner-facing UI (toggle sharing, choose which
  prices to expose, copy the public link, revoke/rotate it) wired into
  computers/show.vue via a new 'Share' button
- share/show.vue: public page rendered with EmptyLayout (no authenticated
  header/sidebar)
- Boolean columns use a  cast since MySQL returns tinyint(1),
  not native booleans, through Lucid
- 6 new functional tests covering: enabling sharing, price visibility
  toggles, disabling sharing revokes the link, cross-user protection on
  the share settings endpoint (404), token rotation invalidating the old
  link, and anonymous access to a shared computer

database/migrations/1784799344283_alter_computers_table.ts

@@ -0,0 +1,23 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+export default class extends BaseSchema {
+  protected tableName = 'computers'
+
+  async up() {
+    this.schema.alterTable(this.tableName, (table) => {
+      table.string('share_token', 64).nullable().unique()
+      table.boolean('share_enabled').notNullable().defaultTo(false)
+      table.boolean('share_show_sell_price').notNullable().defaultTo(false)
+      table.boolean('share_show_cost').notNullable().defaultTo(false)
+    })
+  }
+
+  async down() {
+    this.schema.alterTable(this.tableName, (table) => {
+      table.dropColumn('share_token')
+      table.dropColumn('share_enabled')
+      table.dropColumn('share_show_sell_price')
+      table.dropColumn('share_show_cost')
+    })
+  }
+}

database/schema.ts

@@ -68,7 +68,7 @@ export class ComputerStateSchema extends BaseModel {
 }
 
 export class ComputerSchema extends BaseModel {
-  static $columns = ['cpuScore', 'createdAt', 'globalScore', 'gpuScore', 'id', 'sellPrice', 'stateId', 'title', 'updatedAt', 'userId'] as const
+  static $columns = ['cpuScore', 'createdAt', 'globalScore', 'gpuScore', 'id', 'sellPrice', 'shareEnabled', 'shareShowCost', 'shareShowSellPrice', 'shareToken', 'stateId', 'title', 'updatedAt', 'userId'] as const
   $columns = ComputerSchema.$columns
   @column()
   declare cpuScore: number
@@ -83,6 +83,14 @@ export class ComputerSchema extends BaseModel {
   @column()
   declare sellPrice: number | null
   @column()
+  declare shareEnabled: boolean
+  @column()
+  declare shareShowCost: boolean
+  @column()
+  declare shareShowSellPrice: boolean
+  @column()
+  declare shareToken: string | null
+  @column()
   declare stateId: number
   @column()
   declare title: string