chore: baseline before change C-00001-setup-project

Co-authored-by: Cursor <cursoragent@cursor.com>

.cursor/rules/project-specification.mdc

@@ -0,0 +1,33 @@
+---
+description: go-dns — Go library for dynamic DNS updates (RFC 2136 / nsupdate-style)
+alwaysApply: true
+---
+
+# go-dns — Project Rules
+
+Follow `docs/project-specification.md` for design and implementation.
+
+## Stack
+
+- **Language:** Go (see workspace `go.work` for version)
+- **Module:** `gitea.neitzel.de/konrad/go-dns`
+- **Package:** `godns` (module root)
+- **Type:** Importable Go library (not a standalone service)
+
+## Design
+
+- Target **BIND** and RFC 2136–compatible authoritative nameservers
+- **Dynamic update** (RFC 2136) and **full zone transfer** (AXFR) over DNS
+- **TSIG** authentication with caller-supplied keys (no key generation in library)
+- Typed **RR builders** per record type (not generic rdata strings)
+- Domain names: **ASCII only** in v1
+- UPDATE: **automatic TCP fallback** on UDP truncation
+- Integration tests: **BIND testcontainer** (`go test -tags=integration ./...`)
+- **`docs/bind-tsig-configuration.md`** — BIND `allow-update` / `allow-transfer` guide (implementation phase)
+- Typed **zone data structures** (`Record`, `Zone`, etc.) for transfer/update results
+- Project `.cursor` overrides workspace rules for this module
+
+## Tests
+
+- Unit: `go test ./...`
+- Integration: `go test -tags=integration ./...` — **BIND testcontainer** (Docker required)