feat: Document AST node structure across compiler stages

Add a new Markdown document detailing the AST node structure as it
evolves through the compiler's different stages. This includes a diagram
illustrating the data flow and relationships between the generic
`Node<K, T>` structure and its specialized forms (`UntypedNode`,
`BoundNode`, `TypedNode`, `AnalyzedNode`). The document explains the
`kind` and `ty` payloads for each stage and their significance.

Also removes a deleted file related to a previous optimization plan and
adds new files for future optimization plans.

examples/record_optimizations.myc

@@ -0,0 +1,21 @@
+;; Benchmark: 1.7ms
+;; Benchmark-Repeat: 3
+;; Benchmark: TBD
+;; Tests the effect of record inlining and field lookup optimization
+;; Output: 10000
+(do
+  (macro while [cond body]
+    `(do
+       (def _while_loop (fn []
+         (if ~cond
+             (do ~body (_while_loop))
+             ...)))
+       (_while_loop)))
+
+  (def config {:start 0 :limit 10000 :step 2})
+  (def x (.start config))
+
+  (while (< x (.limit config))
+         (assign x (+ x (.step config))))
+  x
+)