library: client modules end in -client, like protocols end in -protocol

display-client and input-client (files and module names), so a service,
its wire contract, and its client never share a name: `display` the
service, `display-protocol` the contract, `display-client` a program's
view of it. The nine consumers' imports and their packages' declared
lists follow (regenerated from the source scan); build-support's
module_homes table carries the new names.

system/services/display-demo/build.zig

@@ -9,7 +9,7 @@ pub fn build(b: *std.Build) void {
     const exe = build_support.userBinary(b, .{
         .name = "display-demo",
         .root_source_file = b.path("display-demo.zig"),
-        .imports = &.{ "display", "logging", "time" },
+        .imports = &.{ "display-client", "logging", "time" },
     });
     b.installArtifact(exe);
 }

system/services/display-demo/display-demo.zig

@@ -11,7 +11,7 @@
 //! is deliberately independent of the mouse.
 
 
-const display = @import("display");
+const display = @import("display-client");
 const time = @import("time");
 const logging = @import("logging");
 pub fn main() void {