refactor: Add more checks to pre-commit

Updated existing pre-commit hooks and added some new hooks:

- Remove trailing whitespace
- Ensure every non-empty file ends with a new line
- Check YAML file validity
- Prevent adding large files
- Ensure any scripts with shebangs are executable

Added a GitHub action to run pre-commit on every commit. Removed any
existing actions which duplicate pre-commit.

Ran pre-commit on the codebase.

app/boards/arm/s40nc/README.md

@@ -1,9 +1,11 @@
 # S40NC
+
 ![S40NC](https://i.imgur.com/fk8587n.jpg)
 
 Shorty40NoCordy (S40NC) is a limited run 40% bluetooth keyboard originally made and sold by MechWild.
 
 ## Building S40NC ZMK firmware
+
 ```
 west build -p -b s40nc
 ```

app/boards/arm/s40nc/s40nc.keymap

@@ -17,7 +17,7 @@
 / {
 	keymap {
 		compatible = "zmk,keymap";
-		
+
 		default_layer {
 			bindings = <
                 &kp ESC    &kp Q     &kp W     &kp E  &kp R     &kp T      &kp Y   &kp U  &kp I     &kp O     &kp P     &kp BSPC
@@ -35,7 +35,7 @@
                 &trans     &trans     &trans     &kp TAB         &kp TAB         &kp TAB              &kp HOME   &kp PG_DN  &kp END
 			>;
 		};
-        
+
         raise_layer {
 			bindings = <
                 &kp TILDE  &kp EXCL   &kp AT    &kp HASH  &kp DLLR  &kp PRCNT  &kp CARET  &kp AMPS  &kp STAR  &kp LPAR   &kp RPAR   &trans
@@ -44,7 +44,7 @@
                 &trans     &trans     &trans    &kp TAB             &kp TAB               &kp TAB             &kp HOME   &kp PG_DN  &kp END
 			>;
 		};
-        
+
         control_layer {
 			bindings = <
                 &bt BT_CLR    &kp F1        &kp F2           &kp F3      &kp F4    &kp F5  &kp F6  &kp F7     &kp F8   &kp F9        &kp F10       &kp C_PP
@@ -55,4 +55,4 @@
 		};
 	};
 };
-            
+