feat: Projects + stronger LLM placeholder substitution

Backend:
- Project model with defaults: defaultClient, defaultTemplate, defaultBankAccount
- Document gets optional projectId (FK + index)
- Migration 2_projects: enum ProjectStatus + Project table + Document.projectId
- API: /api/projects CRUD, GET /api/projects/:id/documents
- documents/routes filter by projectId

LLM prompt:
- Concrete preamble example: «ООО «...», в лице директора ... , ИП ..., ОГРНИП ...»
  → {{customer.name}}, {{customer.signatoryPosition}} {{customer.signatoryName}},
    {{executor.name}}, {{executor.ogrn}}
- Expanded placeholder list (signatoryName/Position для customer, ogrn etc)
- Side-role detection: «Заказчик» vs «Исполнитель» map to customer/executor

Frontend:
- /projects (list) and /projects/:id (defaults form + documents list under project)
- Nav: «Проекты» first
- DocumentEdit reads projectId from URL, presets default client from project,
  saves projectId with the document

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/prisma/migrations/2_projects/migration.sql

@@ -0,0 +1,37 @@
+-- CreateEnum
+CREATE TYPE "ProjectStatus" AS ENUM ('active', 'completed', 'cancelled');
+
+-- CreateTable
+CREATE TABLE "Project" (
+    "id" UUID NOT NULL,
+    "organizationId" UUID NOT NULL,
+    "name" TEXT NOT NULL,
+    "status" "ProjectStatus" NOT NULL DEFAULT 'active',
+    "defaultClientId" UUID,
+    "defaultTemplateId" UUID,
+    "defaultBankAccountId" UUID,
+    "notes" TEXT,
+    "archivedAt" TIMESTAMP(3),
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "Project_pkey" PRIMARY KEY ("id")
+);
+
+CREATE INDEX "Project_organizationId_archivedAt_idx" ON "Project"("organizationId", "archivedAt");
+CREATE INDEX "Project_organizationId_status_idx" ON "Project"("organizationId", "status");
+
+ALTER TABLE "Project" ADD CONSTRAINT "Project_organizationId_fkey"
+    FOREIGN KEY ("organizationId") REFERENCES "Organization"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+ALTER TABLE "Project" ADD CONSTRAINT "Project_defaultClientId_fkey"
+    FOREIGN KEY ("defaultClientId") REFERENCES "Client"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+ALTER TABLE "Project" ADD CONSTRAINT "Project_defaultTemplateId_fkey"
+    FOREIGN KEY ("defaultTemplateId") REFERENCES "DocumentTemplate"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+ALTER TABLE "Project" ADD CONSTRAINT "Project_defaultBankAccountId_fkey"
+    FOREIGN KEY ("defaultBankAccountId") REFERENCES "BankAccount"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- AlterTable: добавить projectId на Document
+ALTER TABLE "Document" ADD COLUMN "projectId" UUID;
+CREATE INDEX "Document_organizationId_projectId_idx" ON "Document"("organizationId", "projectId");
+ALTER TABLE "Document" ADD CONSTRAINT "Document_projectId_fkey"
+    FOREIGN KEY ("projectId") REFERENCES "Project"("id") ON DELETE SET NULL ON UPDATE CASCADE;