Fix SQL timestamp scanning error on macOS (bd-161, GH-88)

Fixes timestamp scanning error reported in GH-88 where DATETIME columns
were being returned as strings instead of time.Time on macOS 13.5.

Root cause: modernc.org/sqlite driver doesn't recognize mattn-style DSN
parameters (_journal_mode, _foreign_keys). When these incompatible
parameters are present, the driver ignores _time_format=sqlite on some
platforms, causing DATETIME values to remain as strings.

Solution: Use modernc's native _pragma syntax for all database options:
- Changed _journal_mode=WAL to _pragma=journal_mode(WAL)
- Changed _foreign_keys=ON to _pragma=foreign_keys(ON)
- Kept _pragma=busy_timeout(30000) and _time_format=sqlite

This ensures all parameters are properly recognized and DATETIME columns
are automatically parsed to time.Time across all platforms.

Fixes #88

Amp-Thread-ID: https://ampcode.com/threads/T-44d1817a-3709-4f1d-a27a-78bb2fa4d3dc
Co-authored-by: Amp <amp@ampcode.com>

internal/storage/sqlite/sqlite.go

@@ -30,10 +30,12 @@ func New(path string) (*SQLiteStorage, error) {
 	}
 
 	// Open database with WAL mode for better concurrency and busy timeout for parallel writes
+	// Use modernc.org/sqlite's _pragma syntax for all options to ensure consistent behavior
+	// _pragma=journal_mode(WAL) enables Write-Ahead Logging for better concurrency
+	// _pragma=foreign_keys(ON) enforces foreign key constraints
 	// _pragma=busy_timeout(30000) means wait up to 30 seconds for locks instead of failing immediately
-	// Higher timeout helps with parallel issue creation from multiple processes
-	// _time_format=sqlite uses SQLite's native time format for DATETIME columns
-	db, err := sql.Open("sqlite", path+"?_journal_mode=WAL&_foreign_keys=ON&_pragma=busy_timeout(30000)&_time_format=sqlite")
+	// _time_format=sqlite enables automatic parsing of DATETIME columns to time.Time
+	db, err := sql.Open("sqlite", path+"?_pragma=journal_mode(WAL)&_pragma=foreign_keys(ON)&_pragma=busy_timeout(30000)&_time_format=sqlite")
 	if err != nil {
 		return nil, fmt.Errorf("failed to open database: %w", err)
 	}