Fix error handling consistency in auto-import and fallback paths (#47)

* Fix error handling consistency in auto-import and fallback paths

- Add error checking/warnings for auto-import CRUD operations (UpdateIssue, CreateIssue, AddDependency)
- Add error checking/warnings for auto-import label operations (AddLabel, RemoveLabel)
- Add warning when import hash storage fails (prevents unnecessary re-imports)
- Add proper error handling for UserHomeDir with fallback to current directory

These changes make auto-import error handling consistent with manual operations
and prevent silent failures that could confuse users or cause data inconsistencies.

* Remove invalid version property from golangci-lint config

* Fix linter errors: errcheck, unused, goconst, and misspell

- Fix unchecked error returns in ROLLBACK statements
- Fix unchecked type assertion for status field
- Extract LIMIT SQL constant to reduce duplication
- Fix spelling: cancelled -> canceled
- Remove unused ensureCounterInitialized function
- Remove unused parameter in parallel test goroutine

internal/storage/sqlite/sqlite_test.go

@@ -989,7 +989,7 @@ func TestParallelIssueCreation(t *testing.T) {
 	ids := make(chan string, numIssues)
 
 	for i := 0; i < numIssues; i++ {
-		go func(num int) {
+		go func() {
 			issue := &types.Issue{
 				Title:     "Parallel test issue",
 				Status:    types.StatusOpen,
@@ -1003,7 +1003,7 @@ func TestParallelIssueCreation(t *testing.T) {
 			}
 			ids <- issue.ID
 			errors <- nil
-		}(i)
+		}()
 	}
 
 	// Collect results