Print the two shortcuts a dealer had no way to find

Seven keys drive this tool. Five of them are printed on the control they press -- F on
Fold, C on Call, R on Raise, the return arrow on Deal and on Raise to, esc on Cancel.
Two were printed on nothing at all:

  A   opens the amount pad on All-in
  U   takes back the last action

A dealer who learned F, C and R from the buttons had no way to discover the other two
existed. They are the two worth knowing: A is the fastest action in the tool and U is
the one that saves a misclick.

Both are on their controls now. The key lookup matches any of a button's classes, so
the raise pad's four quick amounts can share one class for their looks while only
All-in carries a key.

And a legend in the sidebar, listing all seven with what they do, built from the same
list the handlers are keyed off. There is a test that every key in the map has a line
in the legend and that every line names a key that really is bound -- a shortcut with
no line is one nobody can find, which is the whole bug this fixes.

The panel is hidden on a touch device. A phone has no keys to press, and it is the
same pointer question the touch-target rules ask rather than a guess about width.

One thing I broke and fixed on the way. .actionKey pins itself to the top-right corner
of a big action button. The undo control is a 30px pill with overflow hidden and no
positioning context, so the U escaped it and floated above the action bar -- visible in
the screenshot before I looked properly. It has its own inline class now, checked at
six sizes: the cap sits inside the pill and inside the bar, and the pill is not
clipped.

5 tests (249 total). Driven at six sizes across touch and pointer contexts: the undo
pill shows U, the raise pad shows A on All-in and nothing on Min, half pot and Pot, the
legend lists all seven, and it is display:none on a phone. Contrast clean, layout audit
clean but for the landscape phone already known from #63, no console errors.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_015bnp7xKUPFFSpwkYNFaPgb

JoshHeaps.Net/wwwroot/js/casino/holdem/main.js

@@ -458,6 +458,25 @@ document.addEventListener("DOMContentLoaded", () => {
     // Escape is Modal's job now, for this sheet and the five others that never had it.
     const rulingsOverlay = document.getElementById("rulingsOverlay");
     const closeRulings = () => { rulingsOverlay.hidden = true; };
+    // The shortcut legend, built from the same list the handlers are keyed off, so a
+    // shortcut can't exist without a line here saying what it does.
+    const legend = document.getElementById("shortcutLegend");
+    if (legend) {
+        Shortcuts.LEGEND.forEach(entry => {
+            const term = document.createElement("dt");
+            entry.keys.forEach(key => {
+                const kbd = document.createElement("kbd");
+                kbd.className = "shortcutKey";
+                kbd.textContent = key;
+                term.appendChild(kbd);
+            });
+            const detail = document.createElement("dd");
+            detail.textContent = entry.what;
+            legend.appendChild(term);
+            legend.appendChild(detail);
+        });
+    }
+
     // An index across the top of the rulings sheet, one chip per ruling.
     //
     // This is opened mid-argument with players waiting, and it was nine rulings of