mod: simplify Container and Element creation with updated zterm behavior

src/model.zig

@@ -1,9 +1,32 @@
 //! Model of the `zterm` application.
 
 // TODO planned features:
+// - create change sets (i.e. parse diff headers and provide contents) is the multiarray that what I need?
+// - create `elements.Change` structs which each point to every change associated to a given file (for each file)
 
 // FIX known issues:
 
-const Model = @This();
+content: []const u8,
+changes: std.MultiArrayList(Change) = .empty,
+render_mode: enum {
+    side_by_side,
+    stacked,
+} = .stacked,
 
-pub const init: @This() = .{};
+// TODO alloc-free parsing? (similar to how I've implemented the parser for `smd`?)
+pub const init: Model = .{
+    .content = &.{},
+};
+
+pub const Index = struct {
+    idx: usize,
+    len: usize,
+};
+
+pub const Change = struct {
+    file: Index,
+    diff: Index,
+};
+
+const Model = @This();
+const std = @import("std");