fix(wallets): stop the modal bottom section sliding off-screen after a monitor move

The Wallets modal used the auto-height BeginOverlayDialog overload, whose content
child is AutoResizeY. It sized its table with `tableH = GetContentRegionAvail().y
- 130*dp` INSIDE that child — but on an AutoResizeY child GetContentRegionAvail().y
derives from the child's Size.y, carried over from the previous frame's content
height. That makes tableH self-referential: a fixed point on one monitor, but a
monitor move jumps dpiScale() (the 130*dp reserve + table column/row sizes switch
to new units while the child's Size.y is still old units), knocking it off
equilibrium. With only a lower clamp and no upper bound, the excursion runs
unbounded and pushes the create/folder/footer rows off the bottom.

Give the dialog a FIXED cardHeight (620) via the spec form — the pattern Manage
Portfolio already uses. The content child is then fixed-height (not AutoResizeY),
so GetContentRegionAvail().y is a stable, DPI-current "space left in the card",
tableH stops feeding back, and the fixed-height path already clamps the card to
the viewport (min(cardHeight*dp, vp_size.y-32)). Root-caused via a multi-agent
audit against the ImGui internals.

Verified via the headless sweep at 100% and font_scale 1.5 (150%): the table
absorbs the slack and the create/folder inputs + footer stay on-screen.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ui/windows/wallets_dialog.h

@@ -51,7 +51,19 @@ public:
 
         if (s_needScan) { scan(); s_needScan = false; }
 
-        if (BeginOverlayDialog(TR("wallets_title"), &s_open, 780.0f, 0.94f)) {
+        // FIXED cardHeight (not the auto-height overload): the table below sizes itself from
+        // GetContentRegionAvail().y, which is only stable when the dialog's content child is
+        // fixed-height. Auto-height makes that read self-referential and it diverges across a
+        // monitor move (dpiScale jump), sliding the create/footer rows off-screen. See Manage
+        // Portfolio (market_tab.cpp) for the same fixed-height pattern.
+        OverlayDialogSpec ov;
+        ov.title      = TR("wallets_title");
+        ov.p_open     = &s_open;
+        ov.style      = OverlayStyle::BlurFloat;
+        ov.cardWidth  = 780.0f;
+        ov.cardHeight = 620.0f;
+        ov.idSuffix   = "wallets";
+        if (BeginOverlayDialog(ov)) {
             Type().textColored(TypeStyle::Caption, OnSurfaceMedium(), TR("wallets_intro"));
             ImGui::Dummy(ImVec2(0, Layout::spacingSm()));