comptime type params

TODO.md

@@ -640,10 +640,17 @@
   - v1 intentionally supports integer values only; no comptime branch pruning or
     user-function execution
 
-27.5 comptime type parameters (deferred)
-  - planned shape: `max func($T type, a, b T) T`
+27.5 comptime type parameters (implemented; v1)
+  - `$T type` marks an explicit comptime type parameter in a normal `func` signature:
+    `max func($T type, a, b T) T`
+  - callers pass the type explicitly as an ordinary comptime argument (`max(i32, a, b)`);
+    the type argument specializes the function and is omitted from the runtime ABI
+  - inside the specialization, `T` is visible in parameter, result, local, array, pointer,
+    slice, and fallible type syntax
+  - v1 intentionally keeps `type` contextual to comptime parameter declarations; no
+    inferred type parameters, first-class type values, or comptime execution
 
-27.6 comptime-evaluable constants/functions (deferred)
+27.6 comptime-evaluable constants/functions
   - planned shape: `$x :: 32` and `$sum func(a, b int) int { ... }`
 
 28. brolang build system (requires comptime execution)