feat: Phase 9 - Linking & Backlinks

Implement three new tools for wikilink validation, resolution, and backlink queries:

New Tools:
- validate_wikilinks: Validate all wikilinks in a note with suggestions for broken links
- resolve_wikilink: Resolve a single wikilink to its target path
- backlinks: Get all backlinks to a note with optional unlinked mentions

New Files:
- src/utils/link-utils.ts: Complete wikilink parsing, resolution, and backlink utilities

Modified Files:
- src/tools/vault-tools.ts: Added 3 new methods for link operations
- src/tools/index.ts: Added 3 tool definitions and handlers
- src/types/mcp-types.ts: Added Phase 9 type definitions
- ROADMAP.md: Marked Phase 9 as complete
- CHANGELOG.md: Added v8.0.0 release notes

Key Features:
- Regex-based wikilink parsing with position tracking
- Uses MetadataCache.getFirstLinkpathDest() for accurate resolution
- Fuzzy matching suggestion engine for broken links
- Efficient backlink detection using MetadataCache.resolvedLinks
- Optional unlinked mentions with word-boundary matching
- Context snippet extraction for each occurrence

src/types/mcp-types.ts

@@ -284,3 +284,70 @@ export interface DeleteNoteResult {
 	dryRun: boolean;
 	soft: boolean;
 }
+
+// Phase 9: Linking & Backlinks Types
+
+/**
+ * Resolved wikilink information
+ */
+export interface ResolvedLink {
+	text: string;
+	target: string;
+	alias?: string;
+}
+
+/**
+ * Unresolved wikilink information
+ */
+export interface UnresolvedLink {
+	text: string;
+	line: number;
+	suggestions: string[];
+}
+
+/**
+ * Result from validate_wikilinks operation
+ */
+export interface ValidateWikilinksResult {
+	path: string;
+	totalLinks: number;
+	resolvedLinks: ResolvedLink[];
+	unresolvedLinks: UnresolvedLink[];
+}
+
+/**
+ * Result from resolve_wikilink operation
+ */
+export interface ResolveWikilinkResult {
+	sourcePath: string;
+	linkText: string;
+	resolved: boolean;
+	targetPath?: string;
+	suggestions?: string[];
+}
+
+/**
+ * Backlink occurrence in a file
+ */
+export interface BacklinkOccurrence {
+	line: number;
+	snippet: string;
+}
+
+/**
+ * Backlink from a source file
+ */
+export interface BacklinkInfo {
+	sourcePath: string;
+	type: 'linked' | 'unlinked';
+	occurrences: BacklinkOccurrence[];
+}
+
+/**
+ * Result from backlinks operation
+ */
+export interface BacklinksResult {
+	path: string;
+	backlinks: BacklinkInfo[];
+	totalBacklinks: number;
+}