docs(nerv-theme): fix symbol parity - apply_nerv_theme -> apply_nerv

docs/guide_nerv_theme.md

@@ -105,7 +105,7 @@ This makes operational failures immediately visible without requiring the user t
 Defines the color palette, geometry overrides, and font selection. The application function applies these to the active ImGui style.
 
 ```python
-def apply_nerv_theme() -> None:
+def apply_nerv() -> None:
     style = imgui.get_style()
     style.colors[imgui.Col_.window_bg] = (0.0, 0.0, 0.0, 1.0)
     style.colors[imgui.Col_.text] = (0.88, 0.88, 0.88, 1.0)
@@ -150,8 +150,8 @@ User Menu → Theme → NERV
 Or programmatically:
 
 ```python
-from src.theme_nerv import apply_nerv_theme
-apply_nerv_theme()
+from src.theme_nerv import apply_nerv
+apply_nerv()
 ```
 
 When activated, the active color set, geometry style, and font are swapped. The FX layer is enabled/disabled via the `[nerv].fx_enabled` config flag (default: enabled).
@@ -224,7 +224,7 @@ When the Execution Clutch suspends on a destructive action, the approval modal u
 
 ### Unit Tests
 
-- `tests/test_theme_nerv.py` — `apply_nerv_theme()` correctly sets all colors, geometry, and fonts.
+- `tests/test_theme_nerv.py` — `apply_nerv()` correctly sets all colors, geometry, and fonts.
 - `tests/test_theme_nerv_fx.py` — FX rendering functions don't raise, produce expected output dimensions.
 - `tests/test_theme_nerv_alert.py` — Alert pulse animation runs for the configured duration and decays correctly.