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.

test/system/services/input-test/build.zig

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

test/system/services/input-test/input-test.zig

@@ -7,7 +7,7 @@
 //! device classes to one subscription — source -> service -> subscriber, per device.
 
 const std = @import("std");
-const input = @import("input");
+const input = @import("input-client");
 const logging = @import("logging");
 
 fn writeLine(comptime fmt: []const u8, arguments: anytype) void {