fix: Improve search result processing and error handling

- Refactor core plugin and Omnisearch result processing to use a shared helper function findLineDetails.
- Update error handling in core plugin and Omnisearch search functions to return a "No results found" string instead of throwing an error when no results are found.

src/core/search/regex/ripgrep-regex.ts

@@ -96,7 +96,7 @@ export async function regexSearchFilesWithRipgrep(
 		output = await execRipgrep(rgPath, args)
 	} catch (error) {
 		console.error("Error executing ripgrep:", error)
-		return "No results found"
+		return "No results found."
 	}
 	const results: SearchResult[] = []
 	let currentResult: Partial<SearchResult> | null = null