Improved Balance Patch Handling with gw2fulcrum

Integrate [gw2fulcrum](https://github.com/berdandy/gw2fulcrum) into the website build system

- [ ] If build's balance == config.prev_balance, then run `gw2fulcrum -s patch/CURRENT-BALANCE BUILD.md` and insert into website. For example:

```
❯ gw2fulcrum -s patch/2026-01.txt power-chronomancer.md
power-chronomancer.md was changed:
Time Bomb: This trait replaces Improved Alacrity
Signet of Humility: Reduced the cooldown from 60 seconds to 45 seconds and reduced the defiance damage from 600 to 350 in PvE only.
Well of Senility: Reduced the daze duration from 3 seconds to 2 seconds in PvE only.
```

- [ ] if build's balance == config.prev_balance, and there are zero relevant changes from `gw2fulcrum`, then render the balance label as if build's balance is config.balance (in other words, green with no warning)
- [ ] add gw2fulcrum to site deploy Actions