widgets: canvas draw-list protocol and fifteen more native pages in .t27

specs/widgets/build_receipt.t27

@@ -269,7 +269,7 @@ test the_page_sends_nothing {
 ; NOT carried over: String.prototype.toLowerCase / toUpperCase beyond ASCII and Latin-1 (the tool-name
 ; test and the receipt number); Object.entries order for integer-like keys of `utilisation`, and duplicate keys; a
 ; non-empty string as `utilisation` or `earlier_runs`, and a string as a row of `utilisation`;
-; the data file is cut at DATA_CAP bytes (the page then says it could not be read); a digest longer than
+; the data file is cut at W_DATA_CAP bytes (the page then says it could not be read); a digest longer than
 ; 293 hex digits is cut in the barcode and one longer than 511 bytes everywhere.
 ; MEASURED 2026-10-19: t27c 0.5.2 gen + a 5-line Zig export wrapper + zig build-exe wasm32-freestanding
 ; ReleaseSmall give a 32541-byte wasm. The original page (tool.js) and this one ran in two happy-dom
@@ -292,7 +292,7 @@ test the_page_sends_nothing {
 ; 0 differences. A negative control (one node of the native DOM changed) is caught.
 ; Not compared: the stylesheet (happy-dom); the cases under "NOT carried over".
 
-pub const DATA_CAP : u32 = 32768;
+pub const W_DATA_CAP : u32 = 32768;
 pub var DATA : [32768]u8 = [0; 32768];
 pub var DATA_LEN : u32 = 0;
 pub var DATA_STATE : u8 = 0;
@@ -381,7 +381,7 @@ fn entries_ok(d: []const u8, ut: i64) -> bool {
 }
 
 pub fn w_data(i: u32, s: []const u8) -> u32 {
-    if (s.len > (DATA_CAP as usize)) {
+    if (s.len > (W_DATA_CAP as usize)) {
         DATA_STATE = 2;
         return 0;
     }