feat: parse ISO 8601 ordinal dates (YYYY-DDD)

[Koan-Bot]

What

Add support for ISO 8601 ordinal date format (YYYY-DDD) in Date::Parse.

Why

ISO 8601 defines ordinal dates where DDD is the day-of-year (001-366). This format is commonly used in scientific data, satellite tracking (TLE), CCSDS time codes, and military contexts. Currently str2time("2025-123") returns undef.

How

• Added a new pattern in the strptime heredoc between the ISO week date and ISO compact patterns
• Converts ordinal day-of-year to calendar month/day using timegm/gmtime
• Validates day range (1-366) and rejects day 366 for non-leap years
• Supports optional time suffix (2025-123T10:30:00Z) consistent with other ISO patterns
• Only supports the delimited form (YYYY-DDD) to avoid false positives with 7-digit numbers

Testing

• New t/iso-ordinal-date.t with 26 tests covering:
  • Basic ordinal dates (day 1, 32, 123, 365)
  • Leap year handling (day 366 valid/invalid, Feb 29 boundary)
  • Time suffixes and fractional seconds
  • Invalid inputs (day 0, day 367)
  • Non-interference with existing YYYY-MM-DD parsing
• Full test suite passes

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Quality Report

Changes: 2 files changed, 131 insertions(+)

Code scan: clean

Tests: skipped

Branch hygiene: clean

Generated by Kōan post-mission quality pipeline