Fix race condition in autoCompleteSuggestions.sort() with mutex

Add mutex synchronization to the autoCompleteSuggestions struct to
prevent concurrent modification of slice data during sorting operations.

The sort() method now acquires a lock before performing any sorting
operations, ensuring that only one goroutine can sort the suggestions
at a time. This prevents the data races detected when sort() was called
concurrently.

Changes:
- Add sync.Mutex field to autoCompleteSuggestions struct
- Change sort() receiver from value to pointer to support mutex
- Add Lock/Unlock calls around sorting operations

The test TestAutocompleteSuggestions_ConcurrentSort now passes with
the -race flag, and all existing tests continue to pass.

Fixes #4711

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

pkg/interactive/autocomplete_suggestions.go

@@ -1,8 +1,10 @@
 package interactive
 
 import (
-	"github.com/c-bata/go-prompt"
 	"sort"
+	"sync"
+
+	"github.com/c-bata/go-prompt"
 )
 
 const (
@@ -15,6 +17,7 @@ const (
 )
 
 type autoCompleteSuggestions struct {
+	mu                 sync.Mutex
 	schemas            []prompt.Suggest
 	unqualifiedTables  []prompt.Suggest
 	unqualifiedQueries []prompt.Suggest
@@ -72,7 +75,10 @@ func (s *autoCompleteSuggestions) setQueriesForMod(modName string, queries []pro
 	s.queriesByMod[modName] = queries
 }
 
-func (s autoCompleteSuggestions) sort() {
+func (s *autoCompleteSuggestions) sort() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	sortSuggestions := func(s []prompt.Suggest) {
 		sort.Slice(s, func(i, j int) bool {
 			return s[i].Text < s[j].Text