Scaffold ghp secrets engine modelled on vault-plugin-secrets-gitea

Mints ephemeral, scoped ghp access tokens via ghp's admin token API
(POST /api/tokens), bound to a Vault lease and revoked on lease
expiry (DELETE /api/tokens/{id}).

- config: base_url + write-only admin_token (ghpsvc_ service token),
  TLS settings; verifies the token is a ghp admin on write. No
  rotate-root: the service token is static and operator-managed.
- roles: token_type (agent/proxy), installation_id, app_record_id,
  repositories, scopes (permission:level), session_prefix, ttl/max_ttl.
- creds: mint a lease-bound token; ghp-side duration bounded by the
  lease ceiling as defence in depth.
- secret ghp_token: idempotent revoke + lease renew.
- Unit tests (config/role/creds/client/scopes/revocation), mock-ghp
  e2e on Vault + OpenBao, Woodpecker pre-commit/build/test/release,
  Makefile patch/minor/major, nfpm RPM packaging.

.pre-commit-config.yaml

@@ -0,0 +1,15 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+
+  - repo: https://github.com/dnephin/pre-commit-golang
+    rev: v0.5.1
+    hooks:
+      - id: go-fmt
+      - id: go-vet
+      - id: go-mod-tidy