feat(nwsync): emit blobs and per-artifact NSYM, assemble merged manifests

Adds `crucible nwsync emit` and `crucible nwsync assemble`, the split
replacement for upstream nwn_nwsync_write, which cannot be used because it
wants every hak, the TLK and the module present in one run on one disk.

emit explodes one artifact — a .hak/.erf or a loose file such as the TLK —
into NWSync blobs (NWCompressedBuffer framing, magic NSYC, zstd) plus a NSYM
v3 manifest describing only that artifact, with the same .json sidecar
upstream writes. Blob names are the sha1 of the uncompressed bytes, restypes
nss/ndb/gic are always skipped, an unresolvable restype is a hard error, a
resource over 15 MB fails closed, and no latest or .origin file is ever
written.

assemble merges the per-artifact manifests into one, reading no bulk data.
The merge rule is resref shadowing, not concatenation: a resref present in
more than one artifact resolves to the earliest artifact in --order, the way
the game resolves it. It refuses to merge across mismatched emitter versions,
and takes --group-id from the caller (1 current, 2 testing; 0 is absent).

Refs #53.

internal/dispatch/dispatch.go

@@ -21,6 +21,7 @@ import (
 	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/buildinfo"
 	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/depot"
 	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/menu"
+	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/nwsync"
 )
 
 // Exit codes follow the sysexits(3) convention so CI can distinguish
@@ -104,6 +105,16 @@ var Registry = []Builder{
 		},
 		Wired: true,
 	},
+	{
+		Name:    "nwsync",
+		Bin:     "crucible-nwsync",
+		Summary: "publish NWSync blobs and manifests (emit/assemble)",
+		Commands: []Command{
+			{Name: "emit", Summary: "explode one artifact into blobs plus its own NSYM manifest", Usage: "crucible nwsync emit <artifact> --out DIR"},
+			{Name: "assemble", Summary: "merge per-artifact NSYM manifests into one", Usage: "crucible nwsync assemble --order NAMES --entries DIR --out DIR [--group-id N]"},
+		},
+		Wired: true,
+	},
 	{
 		Name:    "assets",
 		Bin:     "crucible-assets",
@@ -241,7 +252,7 @@ var Registry = []Builder{
 					"2da-to-module [flags] <input.2da> [output.json]",
 					"json-to-2da <input.json> <output.2da>",
 				},
-				Aliases:    []CommandAlias{{Name: "convert-topdata"}},
+				Aliases: []CommandAlias{{Name: "convert-topdata"}},
 			},
 		},
 		Wired: true,
@@ -392,7 +403,7 @@ func runBuilder(name string, args []string, out, errw io.Writer) int {
 		}
 	}
 	if b.Wired {
-		// depot and assets are self-contained builders: they parse their own
+		// depot, assets and nwsync are self-contained builders: they parse their own
 		// subcommands and own their exit contract, bypassing the
 		// b.Commands/delegateLegacy legacy routing entirely.
 		switch b.Name {
@@ -400,6 +411,8 @@ func runBuilder(name string, args []string, out, errw io.Writer) int {
 			return depot.Run(args, out, errw, os.Getenv)
 		case "assets":
 			return assets.Run(args, out, errw, os.Getenv)
+		case "nwsync":
+			return nwsync.Run(args, out, errw)
 		}
 	}
 	if !b.Wired {