v1.5.0: the gym-math release

The gym-math release: eight new calculators, every constant traced to a source you can check.

• prilepin and inol - Prilepin's intensity zones and Hristov's INOL, both quoted verbatim from the 2005 paper that every calculator site copies from (we read the actual PDF; one popular site's variant bands turned out to be fabricated, and the tests pin the paper's own worked examples: 0.9, 0.86, 1.04).
• attempts - meet attempt selection. Opener 91% of your goal third, second 96%: those are the averages of lifters who went 9 for 9 at IPF Worlds (Travis, Zourdos & Bazyler 2021), shown alongside the coach-consensus range so you see the data point and the range real handlers use.
• skinfold - Jackson-Pollock 3-site and 7-site body density plus the Siri equation, sites named explicitly in the output. Sources disagree about which three sites the men's short version uses, so we ship only the combination we could verify and say so.
• tonnage - volume load per session, the "how much weight actually moved" number that complements the session-RPE load math already here.
• pr - e1RM PR detection off the existing six-formula consensus. Log a set, find out if it beat your best.
• clubs - the 1000-lb club and plate milestones, labeled what they are: gym culture, no governing body, still fun to chase.
• gainrate - realistic muscle-gain rates from McDonald's yearly model and the Aragon/Helms monthly model, with the source status of each stated plainly (the internet's favorite "20-25 lb in year one" figure could not be traced to a current primary source, so it isn't here).

One candidate didn't make it: the Casey Butt muscular-potential formula. The primary source is offline and every reachable reproduction is secondhand, so it waits until the real text can be checked. No invented numbers.

All eight ship in the web app too, in 32 UI languages with the math parity-pinned between Python and JavaScript like everything else here.