Add shared engineering rule contracts

- go-logging: slog, server-side only, structured attributes
- go-database: MySQL cursor safety, soft delete, GORM tags, fail-fast, N+1 prevention
- go-background-tasks: Task Manager pattern, polling, no SSE
- go-code-style: layering, error wrapping, startup sequence, config, templating
- import-export: CSV Excel-compatible rules (BOM, semicolon, decimal comma, DD.MM.YYYY)
- table-management: filtering and pagination rules added
- CLAUDE.template.md: updated to reference all shared contracts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

kit/ai/claude/CLAUDE.template.md

@@ -5,7 +5,53 @@ Read and follow the project Bible before making any changes:
 **[`bible/README.md`](bible/README.md)**
 
 The Bible is the single source of truth for architecture, data models, API contracts, and UI
-pattern conventions.
+pattern conventions. Every significant architectural decision must be recorded in the Bible
+decision log before or alongside the code change.
 
-Every significant architectural decision must be recorded in the appropriate Bible decision log.
+---
 
+## Shared Engineering Rules
+
+The following rules apply to ALL changes in this project.
+They are maintained centrally in `tools/ui-design-code/kit/patterns/`.
+
+### Go Code Style
+See [`tools/ui-design-code/kit/patterns/go-code-style/contract.md`](tools/ui-design-code/kit/patterns/go-code-style/contract.md)
+- Handler → Service → Repository layering
+- Error wrapping with `fmt.Errorf("...: %w", err)`
+- Startup sequence: connect DB → migrate → start server
+- Business logic and status thresholds live on the server, not in JS
+
+### Logging
+See [`tools/ui-design-code/kit/patterns/go-logging/contract.md`](tools/ui-design-code/kit/patterns/go-logging/contract.md)
+- Use `slog`, log to binary stdout/stderr only
+- Never use `console.log` as a substitute for server-side logging
+- Always log: startup, background task start/finish/error, export row counts, ingest results
+
+### Database
+See [`tools/ui-design-code/kit/patterns/go-database/contract.md`](tools/ui-design-code/kit/patterns/go-database/contract.md)
+- **CRITICAL**: never execute SQL on the same tx while iterating a cursor — two-phase only
+- Soft delete via `is_active = false`, not physical deletes
+- Fail-fast DB check before starting the HTTP server
+- No N+1 queries: use JOINs or batch `IN` queries
+
+### Background Tasks
+See [`tools/ui-design-code/kit/patterns/go-background-tasks/contract.md`](tools/ui-design-code/kit/patterns/go-background-tasks/contract.md)
+- All slow operations: POST → task_id → client polls `/api/tasks/:id`
+- No SSE — polling only
+- Return `202 Accepted` when task is created
+
+### Tables, Filtering, Pagination
+See [`tools/ui-design-code/kit/patterns/table-management/contract.md`](tools/ui-design-code/kit/patterns/table-management/contract.md)
+- Server-side filtering and pagination only
+- Filter state in URL query params; applying a filter resets to page 1
+- Response must include `total_count`, `page`, `per_page`, `total_pages`
+- Display format: "51–100 из 342"
+
+### CSV Export
+See [`tools/ui-design-code/kit/patterns/import-export/contract.md`](tools/ui-design-code/kit/patterns/import-export/contract.md)
+- UTF-8 BOM required (`\xEF\xBB\xBF`)
+- Semicolon delimiter (`;`), not comma
+- Decimal separator: comma (`1 234,56`), not period
+- Dates as `DD.MM.YYYY`
+- `csv.Writer` with `Comma = ';'`