feat: configurable filter tags for recent files

New 'Filter tags' setting in Recent Files tab. Enter tag names one per line
to pin specific tags as filter pills. Leave empty to auto-detect from
frontmatter 'type' property (existing behavior).

src/settings.ts

@@ -17,6 +17,7 @@ export interface RecentFilesSettings {
 	updateOn: 'file-open' | 'file-edit';
 	omittedPaths: string[];
 	omittedTags: string[];
+	filterTags: string[];  // tags to show as filter pills (empty = auto-detect from frontmatter)
 }
 
 export interface DisplaySettings {
@@ -79,6 +80,7 @@ export const DEFAULT_SETTINGS: WaypointSettings = {
 		updateOn: 'file-open',
 		omittedPaths: [],
 		omittedTags: [],
+		filterTags: [],
 	},
 	display: {
 		rowSize: 26,