v0.12.0 — REST API + personal access tokens

A bidirectional API so other apps (Home Assistant, phone shortcuts, scripts,
and the coming MCP server) can read and update the homestead.

- ApiToken model (sha256-hashed, scoped, with prefix/lastUsed/expiry/revoke)
- authenticateRequest() accepts EITHER a NextAuth cookie session OR a Bearer
  PAT; cookie sessions get full access, tokens are limited to their scopes
  (write implies read; resource and global wildcards). ApiError + handleApiError
- Shared service layer (plants/tasks/locations/plant-types) reused by every
  endpoint and, later, the MCP server — logic lives once
- /api/v1: plants (read + add log), plant-types, locations, tasks (read/create/
  complete), and a whoami/discovery root
- Settings → API tokens: create with per-resource read/write checkboxes, raw
  token shown once, revoke; tokens added to backup/restore
- Pure tests for scope matching + token hashing; verified end-to-end (401/403/
  201, lastUsedAt) against a running server

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

prisma/schema.prisma

@@ -31,6 +31,29 @@ model User {
   mustChangePassword Boolean  @default(false)
   createdAt          DateTime @default(now())
   updatedAt          DateTime @updatedAt
+  apiTokens          ApiToken[]
+}
+
+// ---------------------------------------------------------------------------
+// API tokens — personal access tokens for the REST API + MCP server.
+// Only the SHA-256 hash of the raw token is stored; the raw value (mb_…) is
+// shown once at creation. `scopes` gate what a token can do (e.g. "plants:read").
+// ---------------------------------------------------------------------------
+
+model ApiToken {
+  id         String    @id @default(cuid())
+  name       String    // human label ("Home Assistant", "phone shortcut")
+  tokenHash  String    @unique // sha256(raw)
+  prefix     String    // first 8 chars of the raw token, shown in the UI
+  scopes     String[]  // e.g. ["plants:read","items:write"]; ["*"] = full
+  userId     String
+  user       User      @relation(fields: [userId], references: [id], onDelete: Cascade)
+  lastUsedAt DateTime?
+  expiresAt  DateTime?
+  revokedAt  DateTime?
+  createdAt  DateTime  @default(now())
+
+  @@index([userId])
 }
 
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