mod(structure): update project structure

Remove examples, add description for design goals in README.md and
apply re-names and naming changes accordingly for the project structure.
Implement a flat hierachry, as the library shall remain pretty simple.

src/app.zig

@@ -6,7 +6,7 @@ const event = @import("event.zig");
 const mergeTaggedUnions = event.mergeTaggedUnions;
 const isTaggedUnion = event.isTaggedUnion;
 
-const Key = terminal.Key;
+const Key = @import("key.zig");
 const Queue = @import("queue.zig").Queue;
 
 const log = std.log.scoped(.app);