Add PHP 8.1 explicit octal literal (0o / 0O) support

[TomasVotruba]

The PHP 8 lexer defined hexadecimal (0x) and binary (0b) integer literals but not the PHP 8.1 explicit octal form 0o / 0O. On such input the scanner emitted 0 as T_LNUMBER followed by o... as T_STRING, producing a spurious parse error, e.g. umask(0o077) failed with unexpected T_STRING, expecting ')'.

Change

• Add onum token definition and scanner rule in internal/php8/scanner.rl (base-8 parse, _ separators, overflow falls back to T_DNUMBER like the other bases).
• Regenerate internal/php8/scanner.go via ragel.
• Add TestExplicitOctalTokens.
• Fix stale github.com/TomasVotruba/reco/pkg/token import left in scanner.rl after the module extraction, so regeneration produces the correct rectorphp/php-parser-in-go path.

Notes

The scanner.go diff is large because adding a token rule reshapes the generated ragel state machine. Full suite and golangci-lint pass.