chore: update dependencies and clean up styles

- Added @codemirror/language and @lezer/common as devDependencies in package.json and package-lock.json.
- Removed inline date-calc styling and specific CodeMirror styles from styles.css for a cleaner design.

styles.css

@@ -2,45 +2,6 @@
 Date Calc Plugin Styles
 */
 
-/* Inline date-calc styling for reading view and live preview */
 .date-calc-inline {
-    background-color: var(--background-modifier-accent);
-    border-radius: 3px;
-    padding: 2px 6px;
     color: var(--text-accent);
-    font-weight: bold;
-    font-size: 0.9em;
-    display: inline-block;
-    margin: 0 2px;
-    font-family: var(--font-text);
-}
-
-/* Specific styles for CodeMirror Live Preview widgets */
-.cm-line .date-calc-inline {
-    background-color: var(--background-modifier-accent);
-    color: var(--text-accent);
-    padding: 2px 6px;
-    margin-left: 4px;
-    border-radius: 3px;
-    font-weight: bold;
-    font-size: 0.9em;
-    display: inline;
-    user-select: none;
-    cursor: default;
-    vertical-align: baseline;
-}
-
-/* Additional styling for fenced code blocks */
-.date-calc {
-    background-color: var(--background-modifier-accent);
-    padding: 8px 12px;
-    border-radius: 4px;
-    border-left: 3px solid var(--text-accent);
-    margin: 8px 0;
-}
-
-/* Hover effect to make the result more prominent */
-.date-calc-inline:hover {
-    background-color: var(--background-modifier-hover);
-    color: var(--text-accent-hover);
-}
+}