Reassess blockExoticSubdeps=false once foundry-vtt-types drops git deps

## Summary

Reassess `blockExoticSubdeps: false` in `pnpm-workspace.yaml` and re-enable the
protection once it no longer breaks the install.

## Motivation

pnpm 11 defaults `blockExoticSubdeps` to `true` — a supply-chain protection that
blocks transitive dependencies resolved via exotic protocols (git, direct
tarballs). `@league-of-foundry-developers/foundry-vtt-types` pulls `pixi.js` as a
git-resolved transitive dep, which the protection blocks outright. The setting is
a global boolean with no per-package scope, so disabling it repo-wide was the only
way to make `pnpm install` resolve in the foundry-module merge (#293). That
loosens the protection for every transitive dep, not just foundry-vtt-types.

## Scope

- Re-enable `blockExoticSubdeps` (drop the override, or set it back to `true`)
once one of the unblockers below lands.
- In scope, any of: a `foundry-vtt-types` release that no longer uses git deps;
pinning/vendoring the offending `pixi.js` subdep; a pnpm feature that scopes the
allowance per-package.
- Out of scope: removing `foundry-vtt-types` or changing the Foundry typings
strategy.

## Acceptance criteria

- [ ] `blockExoticSubdeps` is no longer disabled in `pnpm-workspace.yaml`.
- [ ] `pnpm install` resolves cleanly with the protection re-enabled.