version: 0.1.2, from a single constant

Bump for the GetTransaction crash fix, and make the version one value
instead of two literals that could drift.

It was duplicated: cmd/server/main.go had `var version = "0.1.1"` for
--version, and frontend/service.go had "0.1.1-dragonxlightd" inline in
the LightdInfo reply. The gRPC one is the load-bearing copy -- it is
walletrpc/service.proto:48, so every client reads it, and it is the only
way to tell from off-box which build a node is running.

That property is the point of bumping now rather than later. With it, a
rollout can be verified by probing each endpoint over TLS and reading
the advertised version, instead of shelling in to compare binary
checksums, and instead of the only alternative positive test -- calling
GetTransaction on a mempool txid, which proves the fix by crashing any
node that does not have it.

Verified: --version prints 0.1.2, and a GetLightdInfo probe against a
test instance returns 0.1.2-dragonxlightd where production still returns
0.1.1-dragonxlightd.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FU87LdsJZiZkfq1eXubpeo

cmd/server/main.go

@@ -93,7 +93,7 @@ type Options struct {
 }
 
 func main() {
-	var version = "0.1.1" // set version number
+	var version = common.Version
 
 	opts := &Options{}
 	flag.StringVar(&opts.bindAddr, "bind-addr", "127.0.0.1:9069", "the address to listen on")

common/version.go

@@ -0,0 +1,14 @@
+package common
+
+// Version is the single source of truth for this daemon's version.
+//
+// It was previously duplicated as a literal in two places that could drift:
+// cmd/server/main.go's --version output and the Version field of the LightdInfo
+// gRPC reply in frontend/service.go. The gRPC one is the load-bearing copy --
+// it is walletrpc/service.proto:48, so every client and every operator probe
+// reads it, and it is the only way to tell from off-box which build a node is
+// running.
+const Version = "0.1.2"
+
+// VersionString is what GetLightdInfo advertises to clients.
+const VersionString = Version + "-dragonxlightd"

frontend/service.go

@@ -353,7 +353,7 @@ func (s *SqlStreamer) GetLightdInfo(ctx context.Context, in *walletrpc.Empty) (*
 	// TODO these are called Error but they aren't at the moment.
 	// A success will return code 0 and message txhash.
 	return &walletrpc.LightdInfo{
-		Version:                 "0.1.1-dragonxlightd",
+		Version:                 common.VersionString,
 		Vendor:                  "DragonX LightWalletD",
 		TaddrSupport:            true,
 		ChainName:               chainName,