feat: Enhance file search with core plugin and Omnisearch integration

- Introduces a new match_search_files tool for fuzzy/keyword search, integrating with Obsidian's core search plugin and updating Omnisearch integration for improved file search capabilities.
- Adds settings for selecting search backends (core plugin, Omnisearch, ripgrep) for both regex and match searches.
- Updates language files, prompts, and types to support the new functionality.
- Restructures search-related files for better organization.

src/core/search/match/omnisearch-match.ts

@@ -0,0 +1,136 @@
+import { App } from "obsidian";
+import {
+	MAX_RESULTS,
+	truncateLine,
+	SearchResult,
+	formatResults,
+} from '../search-common';
+
+type SearchMatchApi = {
+	match: string;
+	offset: number;
+};
+
+type ResultNoteApi = {
+	score: number;
+	vault: string;
+	path: string;
+	basename: string;
+	foundWords: string[];
+	matches: SearchMatchApi[];
+	excerpt: string;
+};
+
+type OmnisearchApi = {
+	search: (query: string) => Promise<ResultNoteApi[]>;
+	// ... other API methods
+};
+
+declare global {
+	interface Window {
+		omnisearch: OmnisearchApi;
+	}
+}
+
+/**
+ * Checks if the Omnisearch plugin's API is available.
+ * @returns {boolean} True if the API is ready, false otherwise.
+ */
+function isOmnisearchAvailable(): boolean {
+	return window.omnisearch && typeof window.omnisearch.search === "function";
+}
+
+/**
+ * Finds the line number, column number, and content for a given character offset in a file.
+ * @param allLines All lines in the file.
+ * @param offset The character offset of the match.
+ * @returns An object with line number, column number, and the full line content.
+ */
+function findLineAndColumnFromOffset(
+	allLines: string[],
+	offset: number
+): { lineNumber: number; columnNumber: number; lineContent: string } {
+	let charCount = 0;
+	for (let i = 0; i < allLines.length; i++) {
+		const line = allLines[i];
+		// The line ending length (1 for \n, 2 for \r\n) can vary.
+		// A simple +1 is a reasonable approximation for this calculation.
+		const lineEndOffset = charCount + line.length + 1; 
+
+		if (offset < lineEndOffset) {
+			const columnNumber = offset - charCount;
+			return { lineNumber: i, columnNumber, lineContent: line };
+		}
+		charCount = lineEndOffset;
+	}
+	return { lineNumber: -1, columnNumber: -1, lineContent: "" };
+}
+
+/**
+ * Searches using Omnisearch and builds context for each match.
+ * @param query The search query for Omnisearch. Note: Omnisearch does not support full regex.
+ * @param app The Obsidian App instance.
+ * @returns A formatted string of search results.
+ */
+export async function searchFilesWithOmnisearch(
+	query: string,
+	app: App,
+): Promise<string> {
+	try {
+		if (!isOmnisearchAvailable()) {
+			throw new Error(
+				"Omnisearch plugin not found or not active. Please install and enable it to use this search feature."
+			);
+		}
+
+		// Omnisearch is not a regex engine.
+		// The `query` will be treated as a keyword/fuzzy search by the plugin.
+		const apiResults = await window.omnisearch.search(query);
+		if (!apiResults || apiResults.length === 0) {
+			throw new Error("No results found.");
+		}
+
+		const results: SearchResult[] = [];
+
+		for (const result of apiResults) {
+			if (results.length >= MAX_RESULTS) {
+				break; // Stop processing new files if we have enough results
+			}
+			if (!result.matches || result.matches.length === 0) continue;
+
+			const fileContent = await app.vault.adapter.read(result.path);
+			const allLines = fileContent.split("\n");
+
+			for (const match of result.matches) {
+				if (results.length >= MAX_RESULTS) {
+					break; // Stop processing matches if we have enough results
+				}
+
+				const { lineNumber, columnNumber, lineContent } = findLineAndColumnFromOffset(
+					allLines,
+					match.offset
+				);
+
+				if (lineNumber === -1) continue;
+
+				const searchResult: SearchResult = {
+					file: result.path,
+					line: lineNumber + 1, // ripgrep is 1-based, so we adjust
+					column: columnNumber + 1,
+					match: truncateLine(lineContent.trimEnd()),
+					beforeContext: lineNumber > 0 ? [truncateLine(allLines[lineNumber - 1].trimEnd())] : [],
+					afterContext:
+						lineNumber < allLines.length - 1
+							? [truncateLine(allLines[lineNumber + 1].trimEnd())]
+							: [],
+				};
+				results.push(searchResult);
+			}
+		}
+
+		return formatResults(results, ".\\");
+	} catch (error) {
+		console.error("Error during Omnisearch processing:", error);
+		return "An error occurred during the search.";
+	}
+}