fix(build): update Zig version to 0.12.0 and improve build command syntax

Author: sampajano

.gitignore

@@ -13,3 +13,4 @@ target
 .settings
 zig-out
 zig-cache
+.zig-cache

javascript/net/grpc/web/generator/build.zig

@@ -220,8 +220,8 @@ pub fn build(b: *std.Build) void {
             .root = .{ .path = protobuf_dir },
         });
 
-    // Target and optimize configured at creation time above.
-        exe.strip = true;
+        // Target and optimize configured at creation time above.
+        // Install the built artifact (Zig 0.12 API).
         b.installArtifact(exe);
     }
-}
+}