fix: pressing space barely moves input cursor (#1729) (#1733)

## Summary

* **What is the goal of this PR?** 
Fix the visual keyboard cursor not advancing when typing a space. Typing
one space leaves the cursor at position 0; typing two spaces advances it
only by one space width. This affects all input types except URL.
* **What changes are included?** 
Replace `getTextWidth()` with `getTextAdvanceX()` in four locations
within `KeyboardEntryActivity::render()` for cursor positioning and
line-wrapping calculations.

## Additional Context

* **Root cause**: `getTextWidth()` returns the bounding-box width of the
drawn glyphs. The space glyph has `width=0` and `height=0` (it's
invisible), so `getTextWidth(" ") == 0`. The trailing `advanceX` of the
last character is only flushed when the *next* character is processed,
so a string ending in space reports zero width. `getTextAdvanceX()`
correctly includes the final glyph's advance, matching how `drawText()`
actually positions characters.

---

### AI Usage

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Did you use AI tools to help write this code? _**YES**_

src/activities/util/KeyboardEntryActivity.cpp

@@ -421,7 +421,7 @@ void KeyboardEntryActivity::render(RenderLock&&) {
 
   while (true) {
     std::string lineText = displayText.substr(lineStartIdx, lineEndIdx - lineStartIdx);
-    textWidth = renderer.getTextWidth(UI_12_FONT_ID, lineText.c_str());
+    textWidth = renderer.getTextAdvanceX(UI_12_FONT_ID, lineText.c_str(), EpdFontFamily::REGULAR);
     if (textWidth <= maxLineWidth) {
       const bool isLastLine = (lineEndIdx == static_cast<int>(displayText.length()));
       bool isCursorLine = false;
@@ -433,12 +433,14 @@ void KeyboardEntryActivity::render(RenderLock&&) {
         } else {
           beforeCursor = displayText.substr(lineStartIdx, cursorPos - lineStartIdx);
         }
-        int beforeWidth = renderer.getTextWidth(UI_12_FONT_ID, beforeCursor.c_str());
+        int beforeWidth = renderer.getTextAdvanceX(UI_12_FONT_ID, beforeCursor.c_str(), EpdFontFamily::REGULAR);
         int kernOffset = 0;
         if (cursorPos < displayText.length()) {
           std::string beforeAndCursor = beforeCursor + displayText.substr(cursorPos, 1);
-          int beforeAndCursorWidth = renderer.getTextWidth(UI_12_FONT_ID, beforeAndCursor.c_str());
-          int charAdvance = renderer.getTextWidth(UI_12_FONT_ID, displayText.substr(cursorPos, 1).c_str());
+          int beforeAndCursorWidth =
+              renderer.getTextAdvanceX(UI_12_FONT_ID, beforeAndCursor.c_str(), EpdFontFamily::REGULAR);
+          int charAdvance =
+              renderer.getTextAdvanceX(UI_12_FONT_ID, displayText.substr(cursorPos, 1).c_str(), EpdFontFamily::REGULAR);
           kernOffset = beforeAndCursorWidth - beforeWidth - charAdvance;
         }
         if (centerText) {