fix: round the current date to whole seconds so occurrences on the end date are returned

[harrisiirak]

Description

An occurrence falling exactly on endDate is missed when currentDate carries milliseconds (any new Date() in practice): the millisecond remainder is kept through iteration, so the candidate compares as endDate + ms and throws Out of the time span range. The current date is now rounded to whole seconds once per search - up for next(), down for prev() - restoring 4.9.0 behaviour.

Fixes #385

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Testing

• All tests pass (npm test)
• Code coverage is maintained or improved

Changes Made

• CronExpression.#findSchedule - rounds the current date to whole seconds before the search loop; the per-step millisecond handling this made unreachable is removed.
• Three tests: the end-date regression, the sub-second start-date throw, interleaved next/prev anchoring.

[github-actions]

Quality gates · commit 970db12

Coverage

Statements	Branches	Functions	Lines
100%	100%	100%	100%

Benchmark — vs cron-parser@5.7.0 (npm latest)

10000 iterations × 5 samples per pattern. A positive change is faster than the baseline.

Pattern	Baseline	This PR	Change
0 0 0 15 * 5#3	722.03ms	711.16ms	+1.51%
0 0 0 8 * 5#3	686.62ms	678.37ms	+1.20%
0 0 6-20/2,L 2 *	521.09ms	516.66ms	+0.85%
0 0 0 * * 5#3	1217.65ms	1208.81ms	+0.73%
0 0 0 * * 1L,5L	686.40ms	682.00ms	+0.64%
10-30/2 2 12 8 0	156.08ms	155.22ms	+0.55%
0 12 */5 6 *	466.46ms	464.02ms	+0.52%
H H H(9-20)/3 1-11 *	430.66ms	428.67ms	+0.46%
0 0 0 * * 4,6L	344.49ms	343.07ms	+0.41%
0 H * * *	173.35ms	172.64ms	+0.41%
0 15 */5 5 *	450.31ms	449.49ms	+0.18%
10 2 12 8 7	735.04ms	733.91ms	+0.15%
0 H/3 * * *	165.63ms	165.43ms	+0.12%
* * * * * *	52.95ms	52.92ms	+0.06%
0 * * 1,4-10,L * *	93.06ms	94.30ms	-1.34%

_{Informational only. Runner timings are noisy and this check never fails.}