feat(M3): contracts editor, templates, PDF render via Puppeteer/Chromium

Backend:
- numbers.ts — per-org per-doctype per-year sequential numbering (ДГ-2026/001, СЧ-2026/001…)
- money.ts — line totals + Russian rubInWords helper
- documents/routes.ts — CRUD with transactional lines bulk-replace, status changes, history endpoint for client-line autocomplete
- templates/routes.ts — CRUD + instantiate (clones template body into new draft document)
- shared/render/toHtml.ts — block→HTML renderer with placeholder substitution ({{customer.inn}}, {{contract.number}}, {{today}}…)
- documents/pdf.ts — Puppeteer-based PDF rendering with auto-detected Chromium executable
- documents/pdf.routes.ts — GET /:id/preview (HTML) and GET /:id/pdf
- Dockerfile.api — added apk chromium + cyrillic fonts

Web:
- api.ts — Document, DocumentTemplate, Block, LineHistoryItem types
- BlocksEditor — generic block list with reorder/add/remove and per-block forms (heading, party, services_table, totals, terms, signatures, custom_text, page_break)
- LinesEditor — services rows with auto sumCents, "from catalog" picker, "from history by client" panel
- ClientPicker — reusable client dropdown
- pages: Documents list, DocumentEdit (new+existing), Templates list, TemplateEdit
- richtext.ts — plain↔TipTap-JSON conversion (no TipTap yet, just keeps the format compatible)

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

apps/api/package.json

@@ -24,6 +24,7 @@
     "fastify": "^4.28.1",
     "fastify-plugin": "^4.5.1",
     "jose": "^5.9.6",
+    "puppeteer-core": "^24.42.0",
     "zod": "^3.23.8"
   },
   "devDependencies": {