Fix %V (ISO week) parse to honor %u (ISO weekday)

[spokodev]

Description

Parsing the canonical ISO 8601 week-date pattern %G-W%V-%u returns the wrong day: every weekday collapses to the Monday of its ISO week.

d3.utcParse("%G-W%V-%u")("2019-W01-2") // 2018-12-31, should be 2019-01-01
d3.utcParse("%G-W%V-%u")("2019-W01-7") // 2018-12-31, should be 2019-01-06

Round-trip parse(format(d)) is broken for any day that is not the Monday of its ISO week, which is exactly the case a user reaching for ISO 8601 week dates hits.

Root cause

In src/locale.js, the %V reconstruction (if ("V" in d)) computes the day from d.w and defaults d.w = 1 when %w is absent, without consulting a parsed %u (ISO weekday). The sibling %U/%W branch already reads d.u % 7. The %V branch was never given the same treatment, so %V + %u is the only week + weekday combination that does not work (%V + %w and %U/%W + %u are fine).

Fix

-        if (!("w" in d)) d.w = 1;
+        if (!("w" in d)) d.w = "u" in d ? d.u % 7 : 1;

Mirrors the existing %U/%W idiom (d.u % 7, where ISO Sunday 7 maps to 0).

Test

Added %u %V %G cases to the local and UTC parse tests. They fail before the change (weekday ignored, day lands on Monday) and pass after. Full suite stays green under TZ=America/Los_Angeles (148 passing).