feat: Complete DBase4_3DTheme documentation and tests

Added comprehensive documentation, tests, and integration for DBase4_3DTheme:

Documentation:
- Added useDBase4_3DTheme() convenience method to ThemeManager
- Added complete DBase4_3DTheme section to THEMES.md
- Includes historical context, color scheme, 3D features, usage examples

Tests:
- Created DBase4_3DThemeTest.java with 32 comprehensive unit tests
- All tests passing (32/32)
- Tests all Theme3D interface methods
- Verifies authentic dBASE IV colors and 3D rendering

Integration:
- Added DBase4_3DTheme to ThemeCompatibilityIT.java
- Added to ThemeSwitchingIT.java theme switching tests
- Added to UIRenderingWithThemesIT.java rendering tests

Fixes:
- Fixed test expectation for DBase4Theme border characters (ASCII not Unicode)
- Fixed ThemeManager method to call getInstance().setTheme()

Related Issues: #230, #231, #232

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Flossy

THEMES.md

@@ -379,6 +379,79 @@ The shift from black to blue backgrounds was part of a broader trend in late-198
 - Projects celebrating late-1980s/early-1990s database evolution
 - Software requiring a professional blue-background aesthetic
 
+
+## 3D Themes
+
+### Borland 3D Theme
+
+**Historical Context:** Building on the iconic Borland IDE color scheme, this theme adds authentic 3D visual effects inspired by Borland's Turbo Vision framework (1990-1995). Turbo Vision brought windowed interfaces with raised buttons, sunken input fields, and drop shadows to DOS applications.
+
+**Color Scheme:**
+- Background: Yellow on blue (classic Borland desktop)
+- Menus: Cyan on blue (menu bar and buttons)
+- Focused: Black on cyan (inverted selection)
+- Input Fields: White on blue (sunken data entry)
+- Selection: Black on cyan (bright highlight)
+- Shadow: Black on black with A_BOLD (gray simulation)
+- Highlight: White on cyan (raised element top-left edges)
+- Lowlight: Black on cyan (recessed element bottom-right edges)
+
+**3D Features:**
+- Drop shadows (1 column right, 1 row down)
+- Raised buttons and menus
+- Sunken input fields
+- Single-line borders for dialogs
+- Asymmetric border coloring
+
+**Usage:**
+```java
+ThemeManager.useBorland3DTheme();
+
+Dialog dialog = new Dialog("Turbo Pascal 7.0");
+dialog.set3DEnabled(true);
+dialog.setRenderingStyle(RenderingStyle.RAISED);
+```
+
+**When to Use:** Developer tools, IDEs, authentic Turbo Vision recreation.
+
+---
+
+### dBASE IV 3D Theme
+
+**Historical Context:** dBASE IV (1988-1993) revolutionized database software with the Control Center, a graphical menu system featuring 3D-style UI elements similar to Borland's Turbo Vision framework. After Borland acquired Ashton-Tate in 1991, the interface gained even more pronounced 3D effects.
+
+**Color Scheme:**
+- Background: White on blue (Control Center desktop)
+- Menus: Yellow on blue (menu bar and buttons)
+- Focused: Blue on yellow (inverted selection)
+- Input Fields: Cyan on blue (sunken data entry)
+- Selection: Blue on white (browse mode highlights)
+- Shadow: Black on black with A_BOLD (gray simulation)
+- Highlight: White on cyan (raised element top-left edges)
+- Lowlight: Black on cyan (recessed element bottom-right edges)
+
+**3D Features:**
+- Drop shadows (2 columns right, 1 row down)
+- Raised buttons and menus
+- Sunken input fields
+- Double-line borders for modal dialogs
+- Asymmetric border coloring
+
+**Usage:**
+```java
+ThemeManager.useDBase4_3DTheme();
+
+Dialog dialog = new Dialog("Database Configuration");
+dialog.set3DEnabled(true);
+dialog.setRenderingStyle(RenderingStyle.RAISED);
+```
+
+**When to Use:** Professional database applications, business software, authentic dBASE IV recreation.
+
+**Visual Comparison:** More businesslike than Borland3DTheme (white vs yellow background), reflecting database application heritage vs developer tool aesthetic.
+
+---
+
 ---
 
 ## Usage Guide

src/main/java/org/flossware/curses/theme/ThemeManager.java

@@ -208,6 +208,21 @@ public void useBorland3DTheme() {
         setTheme(new Borland3DTheme());
     }
 
+    /**
+     * Sets the current theme to dBASE IV 3D theme.
+     *
+     * <p>This theme recreates the sophisticated windowed interface of dBASE IV 
+     * (1988-1993) with authentic 3D visual effects including drop shadows, raised 
+     * buttons, and sunken input fields. The Control Center's white on blue color 
+     * scheme with yellow menus creates a professional database application aesthetic.</p>
+     *
+     * @see DBase4_3DTheme
+     * @see useDBase4Theme()
+     */
+    public static void useDBase4_3DTheme() {
+        getInstance().setTheme(new DBase4_3DTheme());
+    }
+
     /**
      * Switches to the Modern theme.
      *

src/test/java/org/flossware/curses/integration/ThemeCompatibilityIT.java

@@ -54,7 +54,8 @@ static Stream<Theme> allThemes() {
             new TRS80Theme(),
             new DOSTheme(),
             new DBase3Theme(),
-            new DBase4Theme()
+            new DBase4Theme(),
+            new DBase4_3DTheme()
         );
     }
 

src/test/java/org/flossware/curses/integration/ThemeSwitchingIT.java

@@ -38,7 +38,8 @@ class ThemeSwitchingIT extends IntegrationTestBase {
         new ThemeSupplier("TRS-80", TRS80Theme::new),
         new ThemeSupplier("DOS", DOSTheme::new),
         new ThemeSupplier("dBASE III", DBase3Theme::new),
-        new ThemeSupplier("dBASE IV", DBase4Theme::new)
+        new ThemeSupplier("dBASE IV", DBase4Theme::new),
+        new ThemeSupplier("dBASE IV 3D", DBase4_3DTheme::new)
     );
 
     /**

src/test/java/org/flossware/curses/integration/UIRenderingWithThemesIT.java

@@ -38,7 +38,8 @@ static Stream<Arguments> allThemes() {
             Arguments.of(new TRS80Theme(), "TRS-80"),
             Arguments.of(new DOSTheme(), "DOS"),
             Arguments.of(new DBase3Theme(), "dBASE III"),
-            Arguments.of(new DBase4Theme(), "dBASE IV")
+            Arguments.of(new DBase4Theme(), "dBASE IV"),
+            Arguments.of(new DBase4_3DTheme(), "dBASE IV 3D")
         );
     }
 
@@ -52,7 +53,8 @@ static Stream<Arguments> asciiThemes() {
             Arguments.of(new TRS80Theme(), "TRS-80"),
             Arguments.of(new DOSTheme(), "DOS"),
             Arguments.of(new DBase3Theme(), "dBASE III"),
-            Arguments.of(new DBase4Theme(), "dBASE IV")
+            Arguments.of(new DBase4Theme(), "dBASE IV"),
+            Arguments.of(new DBase4_3DTheme(), "dBASE IV 3D")
         );
     }