feat(keymap): add mod-morph behaviors and adjust layers

- Introduce mmshr behavior for right shift mod-morph Implement
- Tab/Caps and Bspc/DEL morphing in base layer Clean up symbol layer
- by removing redundant bindings

Author: chuxubank

config/silakka54.keymap

@@ -19,6 +19,12 @@
             mods = <(MOD_LGUI|MOD_LSFT|MOD_RGUI|MOD_RSFT)>;
             keep-mods = <(MOD_LGUI|MOD_RSFT)>;
         };
+        mmshr: mod_morph_shift_right {
+            compatible = "zmk,behavior-mod-morph";
+            #binding-cells = <2>;
+            bindings = <&kp>, <&kp>;
+            mods = <(MOD_RSFT)>;
+        };
         mo_tog: behavior_mo_tog {
             compatible = "zmk,behavior-hold-tap";
             #binding-cells = <2>;
@@ -39,10 +45,10 @@
 // | SHIFT |  Z  |  X  |  C   |  V   |  B   |           |  N   |  M    |  ,    |  .   |   /   | SHIFT |
 //                     | ALT  | GUI  | LOWER|           | ENTER| SPACE | RAISE |
             bindings = <
-&gresc    &kp N1 &kp N2 &kp N3   &kp N4   &kp N5        &kp N6   &kp N7    &kp N8    &kp N9  &kp N0   &kp MINUS
-&kp TAB   &kp Q  &kp W  &kp E    &kp R    &kp T         &kp Y    &kp U     &kp I     &kp O   &kp P    &kp BSPC
-&kp LCTRL &kp A  &kp S  &kp D    &kp F    &kp G         &kp H    &kp J     &kp K     &kp L   &kp SEMI &kp SQT
-&kp LSHFT &kp Z  &kp X  &kp C    &kp V    &kp B         &kp N    &kp M     &kp COMMA &kp DOT &kp FSLH &kp RSHFT
+&gresc           &kp N1 &kp N2 &kp N3   &kp N4   &kp N5        &kp N6   &kp N7    &kp N8    &kp N9  &kp N0   &kp MINUS
+&mmshr TAB CAPS  &kp Q  &kp W  &kp E    &kp R    &kp T         &kp Y    &kp U     &kp I     &kp O   &kp P    &mmshr BSPC DEL
+&kp LCTRL        &kp A  &kp S  &kp D    &kp F    &kp G         &kp H    &kp J     &kp K     &kp L   &kp SEMI &kp SQT
+&kp LSHFT        &kp Z  &kp X  &kp C    &kp V    &kp B         &kp N    &kp M     &kp COMMA &kp DOT &kp FSLH &kp RSHFT
                         &kp LALT &kp LGUI &mo 1         &kp RET  &kp SPACE &mo_tog 2 3
             >;
         };
@@ -62,7 +68,7 @@
             display-name = "Symbol";
             bindings = <
 &kp GRAVE &trans &trans &trans &trans &trans    &trans &trans &trans &kp MINUS &kp EQUAL &kp BSLH
-&kp CAPS  &trans &trans &trans &trans &trans    &trans &trans &trans &kp LBKT  &kp RBKT  &kp DEL
+&trans    &trans &trans &trans &trans &trans    &trans &trans &trans &kp LBKT  &kp RBKT  &trans
 &trans    &trans &trans &trans &trans &trans    &trans &trans &trans &kp LBRC  &kp RBRC  &trans
 &trans    &trans &trans &trans &trans &trans    &trans &trans &trans &trans    &trans    &trans
                         &trans &trans &trans    &trans &trans &trans