Add LocalDate and sub-second precision support.

[gustavofreze]

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Summary

What this pull request does.

Related issue

Closes #...

Checklist

• Tests added or updated.
• Documentation updated when applicable.
• composer review passes.
• composer tests passes.

[Copilot]

Pull request overview

Adds two major capabilities to the tiny-blocks Time library: a new LocalDate value object for date-only modeling, and configurable ISO-8601 emission precision for Instant (seconds/milliseconds/microseconds), including decoding of fractional seconds.

Changes:

• Introduces LocalDate (+ InvalidLocalDate) and documentation/tests for date-only operations and projecting an Instant into a civil date.
• Adds Precision and extends Instant::toIso8601() to optionally emit milliseconds/microseconds; updates offset datetime decoding to accept fractional seconds.
• Refactors multiple unit tests toward more explicit Given/When/Then steps and expands Instant coverage for precision formatting.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
tests/Unit/TimezonesTest.php	Refactors assertions/BDD step annotations for Timezones.
tests/Unit/TimeOfDayTest.php	Refactors assertions/BDD step annotations for TimeOfDay.
tests/Unit/PeriodTest.php	Minor refactor of overlap/contains assertions to store intermediate results.
tests/Unit/LocalDateTest.php	New comprehensive unit test suite for LocalDate.
tests/Unit/InstantTest.php	Adds Precision coverage and more fractional-second parsing/formatting tests.
tests/Unit/DurationTest.php	Refactors assertions/BDD steps for Duration comparisons and accessors.
tests/Unit/DayOfWeekTest.php	Refactors tests using cases()/array helpers and explicit intermediate variables.
src/Timezones.php	PHPDoc wording tweaks for factories and toStrings().
src/Timezone.php	PHPDoc wording tweaks for toString() / toDateTimeZone().
src/TimeOfDay.php	PHPDoc wording tweaks + renames local $diff to $difference in durationUntil().
src/Precision.php	New public enum to represent ISO-8601 emission granularity.
src/LocalDate.php	New public value object for date-only operations (parse/format/compare/day arithmetic).
src/Internal/Decoders/OffsetDateTimeDecoder.php	Adds fractional-second decoding for offset ISO-8601 instants.
src/Instant.php	Adds Precision support in toIso8601() and introduces toLocalDate().
src/Exceptions/InvalidLocalDate.php	New exception type for invalid local-date parsing/component validation.
README.md	Documents Precision usage and introduces LocalDate section + updates license link.
phpstan.neon.dist	Adds a suppression targeting Instant::fromUnixSeconds() return type handling.
.claude/rules/php-library-testing.md	Clarifies allowed non-test methods (lifecycle hooks + data providers).
.claude/rules/php-library-code-style.md	Updates member-ordering rule semantics and Internal/ PHPDoc guidance.

Comments suppressed due to low confidence (2)

src/Timezones.php:114

• toStrings() returns a list of IANA identifiers; the summary "Returns the Timezones as strings" is vague compared to the previous wording. Consider restoring the more specific description (identifiers as plain strings) so the PHPDoc matches the return type semantics.

    /**
     * Returns the Timezones as strings.
     *
     * @return list<string> The list of IANA timezone identifier strings.
     */
    public function toStrings(): array

tests/Unit/InstantTest.php:1025

• This data set calls toIso8601(precision: Precision::Seconds), but Seconds is the method default. Per the code-style rules, default-valued arguments should be omitted; the default behavior is already covered by testToIso8601DefaultPrecisionIsSeconds(). Consider removing this case or switching it to the no-argument call.

            'Seconds precision, no fractions emitted'                 => [
                'value'           => '2026-02-17 08:27:21.106011',
                'precision'       => Precision::Seconds,
                'expectedIso8601' => '2026-02-17T08:27:21+00:00'
            ],