feat(ui): settings polish — button retune, daemon card, RPC 2-row, chat preview

Settings tabs brought closer to the approved mockup:
- ActionButton/renderCardButton retune (settings-scoped): 7px radius, 9px
  padX, Primary → accent-outline chip, Secondary/card buttons more defined.
- Daemon-binary card: compact status right-aligned on the DAEMON BINARY
  heading (Up to date / Version differs / Not installed), filled/rounded
  status box, neutral danger divider (was alarming red), roomier spacing.
- RPC Connection: two-row column-aligned layout (Host | Port, then
  Username | Password) so the password no longer clips off the card edge.
- Chat settings tab: live conversation preview below the Appearance /
  Messaging cards; "Focus input on open" checkbox reflowed onto the console
  color-toggle row.
- Debug Options: "Current theme only" toggle restricts either screenshot
  sweep to the active theme instead of cycling every skin.
- Tabs fill the full content width (content-max-width cap disabled) and the
  sidebar nav panel centers within the true visible area.
- i18n: new keys for the above (untranslated keys fall back to English).

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

src/ui/layout.h

@@ -173,11 +173,11 @@ inline float kSidePanelMinWidth()   { return schema::UI().drawElement("panels",
 inline float kSidePanelMaxWidth()   { return schema::UI().drawElement("panels", "side-panel").getFloat("max-width", 450.0f) * dpiScale(); }
 inline float kSidePanelWidthRatio() { return schema::UI().drawElement("panels", "side-panel").getFloat("width-ratio", 0.4f); }
 
-// Overall content-column cap: the max width a tab's content should occupy before it is centered in wider
-// windows. Prevents cards/forms/tables (which all derive their size from the content child's width) from
-// stretching edge-to-edge at wide/ultrawide widths. <= 0 disables (fill full width). Tunable via ui.toml
-// [layout] content-max-width; default is generous so data-dense screens stay comfortable.
-inline float kContentMaxWidth() { return schema::UI().drawElement("layout", "content-max-width").sizeOr(1600.0f) * dpiScale(); }
+// Overall content-column cap: the max width a tab's content occupies before it is centered in wider
+// windows. <= 0 disables the cap so tab content fills ALL available horizontal width (the default —
+// requested so large windows don't leave a big empty gutter on the right). Set a positive
+// ui.toml [layout] content-max-width to re-enable a centered readable column.
+inline float kContentMaxWidth() { return schema::UI().drawElement("layout", "content-max-width").sizeOr(0.0f) * dpiScale(); }
 
 // Shared compose-card envelope for the Send + Receive tabs (and any tab wanting the same box): fill the
 // available column up to the content-max-width cap, then center the leftover as margin. Both tabs MUST
@@ -186,7 +186,8 @@ inline float kContentMaxWidth() { return schema::UI().drawElement("layout", "con
 // Receive on any window wider than ~860dp. Returns {width, offsetX} in the same units as availW.
 struct CardBox { float width; float offsetX; };
 inline CardBox mainComposeCardBox(float availW) {
-    float w = std::min(availW, kContentMaxWidth());
+    float cap = kContentMaxWidth();
+    float w = (cap > 0.0f) ? std::min(availW, cap) : availW;  // cap <= 0 -> fill full width
     return CardBox{ w, std::max(0.0f, (availW - w) * 0.5f) };
 }