add ArrayList alias to std

TODO.md

@@ -814,7 +814,14 @@
   - `read` and `write` validate provider counts; `write_all` handles partial writes and no progress
   - the system provider uses unbuffered libc `read`/`write`, retries interruption, and allocates nothing
 
-34. re-exports so `std` can re-export e.g. `ArrayList(T)`, so users can do `std.ArrayList(i32)` instead of `std.arraylist.ArrayList(i32)`, while still using `std.arraylist.append(&values, 420)`. thinking this would be nice ergonomically.
+34. package declaration aliases and root `std.ArrayList` (implemented)
+  - bare qualified aliases use `Name :: alias package.Member` without adding a keyword
+  - functions/type factories, named types, and globals transparently retain the target identity;
+    mutable global aliases therefore share the original storage
+  - aliases resolve transitively at load time, consume their file-local import, preserve leading-
+    underscore visibility, and diagnose missing, hidden, unavailable, ambiguous, cyclic, or
+    conflicting targets
+  - root `std` re-exports only `ArrayList(T)` for now; operations remain under `std/arraylist`
 
 ## A word on unchecked casts