fix(uuid): reject timestamps that exceed 48 bits in v7.generate()

[tomas-zijdemans]

generate() in @std/uuid/v7 silently truncates timestamps to 48 bits. This PR makes it throw a RangeError instead.

The timestamp is written with setBigUint64, which wraps modulo 2^64, so any bit above 48 disappears without a trace:

• generate(2 ** 48) returns a UUID whose extractTimestamp() is 0
• generate(Date.now() * 1000) (microseconds passed by mistake) returns a UUID carrying a garbage timestamp

Both results pass validate(), so nothing downstream catches the corruption.

The fix extends the existing guard: generate() already threw RangeError for negative and non-integer timestamps, and now also rejects values above 2 ** 48 - 1. The @throws doc states the full range, and tests cover the new throw path plus a round-trip at the maximum value.

On the behavior change: inputs that previously produced a corrupted UUID now throw. An inline comment said "truncated to 48 bits", but the truncation never made it into the public JSDoc, and it breaks the round-trip the tests already assert (extractTimestamp(generate(t)) === t). I read that comment as describing the bug, not the contract. Since 2 ** 48 - 1 milliseconds lands in the year 10889, no wall-clock timestamp is affected. Only mistakes are.

I used Claude Code to help investigate and write this change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.03%. Comparing base (ca58f94) to head (b4ac8b1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7284      +/-   ##
==========================================
- Coverage   95.03%   95.03%   -0.01%     
==========================================
  Files         617      619       +2     
  Lines       51637    51897     +260     
  Branches     9359     9410      +51     
==========================================
+ Hits        49075    49322     +247     
- Misses       2021     2030       +9     
- Partials      541      545       +4     

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