mcp: expose m2pack_* tools in the mcp server

Add four ToolSpec entries (m2pack_build, m2pack_verify, m2pack_diff,
m2pack_export_runtime_key) mirroring the CLI argparse signatures.
server.py auto-enumerates TOOL_SPECS so no wiring change needed.

src/metin_release_mcp/tool_defs.py

@@ -64,6 +64,7 @@ class ToolSpec:
 # ---------------------------------------------------------------------------
 
 _RELEASE = ("release",)
+_M2PACK = ("m2pack",)
 
 
 TOOL_SPECS: tuple[ToolSpec, ...] = (
@@ -164,6 +165,54 @@ TOOL_SPECS: tuple[ToolSpec, ...] = (
             FieldSpec("dry_run_upload", "boolean", description="rsync --dry-run for upload + promote."),
         ),
     ),
+    ToolSpec(
+        name="m2pack_build",
+        subcommand=_M2PACK + ("build",),
+        description="Build a signed .m2p archive from a client asset directory via m2pack-secure.",
+        fields=(
+            FieldSpec("input", "path", required=True, description="Client asset source directory."),
+            FieldSpec("output", "path", required=True, description="Output .m2p archive path."),
+            FieldSpec("key", "path", required=True, description="Master content key file."),
+            FieldSpec(
+                "sign_secret_key",
+                "path",
+                required=True,
+                description="Ed25519 signing secret key file.",
+            ),
+            FieldSpec("key_id", "integer", description="Content key id (default 1)."),
+        ),
+    ),
+    ToolSpec(
+        name="m2pack_verify",
+        subcommand=_M2PACK + ("verify",),
+        description="Verify an .m2p archive's manifest signature and optionally full decrypt.",
+        fields=(
+            FieldSpec("archive", "path", required=True, description="Path to .m2p archive."),
+            FieldSpec("public_key", "path", description="Ed25519 public key file."),
+            FieldSpec("key", "path", description="Master content key file for full-decrypt verify."),
+        ),
+    ),
+    ToolSpec(
+        name="m2pack_diff",
+        subcommand=_M2PACK + ("diff",),
+        description="Diff two directories and/or .m2p archives (left vs right).",
+        fields=(
+            FieldSpec("left", "path", required=True, description="Left side: directory or .m2p archive."),
+            FieldSpec("right", "path", required=True, description="Right side: directory or .m2p archive."),
+        ),
+    ),
+    ToolSpec(
+        name="m2pack_export_runtime_key",
+        subcommand=_M2PACK + ("export-runtime-key",),
+        description="Export a launcher runtime-key payload (json or blob form) from master+public keys.",
+        fields=(
+            FieldSpec("key", "path", required=True, description="Master content key file."),
+            FieldSpec("public_key", "path", required=True, description="Ed25519 public key file."),
+            FieldSpec("output", "path", required=True, description="Output payload path."),
+            FieldSpec("key_id", "integer", description="Content key id (default 1)."),
+            FieldSpec("format", "string", description="Payload format: json or blob (default json)."),
+        ),
+    ),
 )