feat: exact-match-first ranking in search and wikilink autocomplete

Add searchRank/bestSearchRank utilities that compute a tier (0=exact,
1=prefix, 2=fuzzy-only). Both useNoteSearch and WikilinkChatInput now
sort by rank tier first, then by fuzzy score, ensuring notes with exact
title or alias matches always surface above partial/fuzzy matches.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/utils/fuzzyMatch.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest'
-import { fuzzyMatch } from './fuzzyMatch'
+import { fuzzyMatch, searchRank, bestSearchRank } from './fuzzyMatch'
 
 describe('fuzzyMatch', () => {
   it('matches exact string', () => {
@@ -44,3 +44,43 @@ describe('fuzzyMatch', () => {
     expect(fuzzyMatch('a', '').match).toBe(false)
   })
 })
+
+describe('searchRank', () => {
+  it('returns 0 for exact match', () => {
+    expect(searchRank('Refactoring', 'Refactoring')).toBe(0)
+  })
+
+  it('returns 0 for case-insensitive exact match', () => {
+    expect(searchRank('refactoring', 'Refactoring')).toBe(0)
+  })
+
+  it('returns 1 for prefix match', () => {
+    expect(searchRank('Refactoring', 'Refactoring Ideas')).toBe(1)
+  })
+
+  it('returns 1 for case-insensitive prefix match', () => {
+    expect(searchRank('quarter', 'Quarter Review')).toBe(1)
+  })
+
+  it('returns 2 for non-prefix fuzzy match', () => {
+    expect(searchRank('Ideas', 'Refactoring Ideas')).toBe(2)
+  })
+})
+
+describe('bestSearchRank', () => {
+  it('returns best rank across title and aliases', () => {
+    expect(bestSearchRank('ref', 'Refactoring Notes', ['ref'])).toBe(0)
+  })
+
+  it('returns title rank when no aliases match better', () => {
+    expect(bestSearchRank('Refactoring', 'Refactoring', [])).toBe(0)
+  })
+
+  it('prefers alias exact match over title prefix match', () => {
+    expect(bestSearchRank('ref', 'Reference Manual', ['ref'])).toBe(0)
+  })
+
+  it('returns 2 when nothing matches as exact or prefix', () => {
+    expect(bestSearchRank('ideas', 'Refactoring Ideas', ['thoughts'])).toBe(2)
+  })
+})

src/utils/fuzzyMatch.ts

@@ -1,3 +1,22 @@
+/** Search rank tier: 0 = exact match, 1 = prefix match, 2 = fuzzy only. Lower is better. */
+export function searchRank(query: string, target: string): number {
+  const q = query.toLowerCase()
+  const t = target.toLowerCase()
+  if (t === q) return 0
+  if (t.startsWith(q)) return 1
+  return 2
+}
+
+/** Best rank across a title and its aliases. */
+export function bestSearchRank(query: string, title: string, aliases: string[]): number {
+  let rank = searchRank(query, title)
+  for (const alias of aliases) {
+    rank = Math.min(rank, searchRank(query, alias))
+    if (rank === 0) break
+  }
+  return rank
+}
+
 /** Fuzzy match: all query chars must appear in order in the target. */
 export function fuzzyMatch(query: string, target: string): { match: boolean; score: number } {
   const q = query.toLowerCase()