Add passv: a Vault-backed drop-in for pass

Provide a password-store CLI that keeps pass's on-disk layout (<name>.gpg
binary OpenPGP under $PASSWORD_STORE_DIR) but routes all encryption and
decryption through a vault-plugin-secrets-gpg engine mount, so the GPG private
key never lives on the client.

- Implement init/show/ls/insert/generate/edit/rm/mv/cp/find/grep/git with
  pass-compatible flags and implicit `passv <name>`=show dispatch.
- Resolve the recipient from a Vault ref: .gpg-id holds <mount>/<key> for
  passv-native stores, or a sibling .vault-id lets a store keep real GPG
  fingerprints in .gpg-id for dual gpg+Vault use.
- mv/cp re-encrypt across differing recipients; same-recipient moves copy the
  ciphertext verbatim.
- Ship the sibling build/packaging/CI: nfpm RPM to /usr/bin/passv (artifactapi
  rpm-internal on v* tag), Woodpecker PR/release pipelines, unit tests plus a
  real-Vault e2e that also proves dual gpg+Vault decryption.
- README covers store creation, migrating a GPG pass store, and dual-mode.

Makefile

@@ -0,0 +1,65 @@
+.PHONY: build install test lint fmt clean tidy rpm rpm-package patch minor major check-go e2e
+
+BINARY := passv
+PKG := .
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo "0.0.0-dev")
+OS ?= $(shell go env GOOS)
+ARCH ?= $(shell go env GOARCH)
+PLUGIN_DIR ?= ./dist
+
+GO_VERSION_REQUIRED := 1.25
+GO_VERSION_ACTUAL := $(shell go version | sed 's/go version go\([0-9]*\.[0-9]*\).*/\1/')
+
+check-go:
+	@if [ "$$(printf '%s\n%s' "$(GO_VERSION_REQUIRED)" "$(GO_VERSION_ACTUAL)" | sort -V | head -1)" != "$(GO_VERSION_REQUIRED)" ]; then \
+		echo "ERROR: Go >= $(GO_VERSION_REQUIRED) required, found $(GO_VERSION_ACTUAL)"; exit 1; \
+	fi
+
+build: check-go tidy
+	CGO_ENABLED=0 GOOS=$(OS) GOARCH=$(ARCH) go build -ldflags="-s -w -X main.version=$(VERSION)" -o $(PLUGIN_DIR)/$(BINARY) $(PKG)
+
+install: build
+	install -Dm0755 $(PLUGIN_DIR)/$(BINARY) $(DESTDIR)/usr/bin/$(BINARY)
+
+test: check-go
+	go test -race -count=1 ./...
+
+lint: check-go
+	go vet ./...
+
+fmt: check-go
+	gofmt -w .
+
+tidy:
+	go mod tidy
+
+clean:
+	rm -rf $(PLUGIN_DIR)
+
+rpm: build rpm-package
+
+rpm-package:
+	./scripts/build-rpm.sh $(VERSION)
+
+# End-to-end test drives the real passv binary against a Vault dev server
+# running the vault-plugin-secrets-gpg engine.
+e2e:
+	./scripts/e2e.sh
+
+_LATEST := $(shell git tag --sort=-v:refname | grep -E '^v[0-9]+\.[0-9]+\.[0-9]+$$' | head -1)
+_BASE   := $(if $(_LATEST),$(_LATEST),v0.0.0)
+_MAJ    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f1)
+_MIN    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f2)
+_PAT    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f3)
+
+patch:
+	@NEW=v$(_MAJ).$(_MIN).$(shell expr $(_PAT) + 1); \
+	git tag $$NEW && echo "Tagged $$NEW" && git push origin $$NEW
+
+minor:
+	@NEW=v$(_MAJ).$(shell expr $(_MIN) + 1).0; \
+	git tag $$NEW && echo "Tagged $$NEW" && git push origin $$NEW
+
+major:
+	@NEW=v$(shell expr $(_MAJ) + 1).0.0; \
+	git tag $$NEW && echo "Tagged $$NEW" && git push origin $$NEW