Correct card generation facts on the rarity page

[ptrlrd]

What

Fixes the factual errors on the Card Rarity Odds mechanics page and adds the missing card sources. This came out of issues #254, #251, and #235.

I verified everything against the decompiled game code (CardRarityOdds, CardFactory.CreateForReward, and the event/relic model classes) rather than from memory, since the page had a few things wrong.

Changes

• Rewrote the "random card" section into the three behaviors that actually exist (it claimed two):
  1. Default odds: rolls a rarity at fixed base rates with no pity offset. The non-combat path uses RollWithBaseOdds, which checks the rare and uncommon thresholds separately instead of stacking them, so it realizes ~63/34/3, not the 60/37/3 on combat rewards.
  2. True whole-pool uniform: every eligible card equally likely (All Star).
  3. Fixed rarity, uniform within rarity: the reward's rarity is pinned, not rolled.
• Recategorized Glass Eye and Sea Glass. They were listed as free uniform pulls across the whole pool. They are actually fixed-rarity per reward (Glass Eye C/C/U/U/R, Sea Glass C/U/R), uniform within each rarity.
• Added Colorful Philosophers ([Feature] Add Colorful Philosophers to Card Rarity Odds page #254): pick another character's color, get a Common/Uncommon/Rare reward set from that pool.
• Added Crystal Sphere ([Feature] Cyrstal Sphere Addition #235): three card rewards on the dig grid pinned to Common/Uncommon/Rare, same mechanism as Glass Eye.
• Clarified Brain Leech ([Feature] Clarify Brain Leech Randomization Mode #251): both options use default odds and neither touches the offset. Share Knowledge is 5 from the character's own pool, Rip is a 3-card colorless reward.
• Documented the uncommon-clipping behavior: the rare threshold is not floored at 0 before the uncommon band stacks on it, so uncommon dips below its nominal value at a fresh regular-fight reset.

Note for follow-up

The ~63/34/3 default-odds split looks like a latent bug in the game itself: combat's Roll stacks the rare and uncommon thresholds, but RollWithBaseOdds does not. Documented as-is for now since it is what the code does.

Closes #235
Closes #251
Closes #254