Sweep of website/ deps to latest within ranges, plus a vite downgrade
from 8 -> 7 to match astro's transitive vite (7.3.2) and avoid a
rolldown regression with @tailwindcss/vite 4.2.4.

Closes alerts #28 #29 #30 #31 #33 #34 #35 #36 #37 #38 #39 #40 #44 #48
covering vite, picomatch, postcss, yaml, astro, smol-toml.

- vite ^8.0.1 -> ^7.3.2 (drops the now-redundant vite 8 lineage; astro
  pulls 7.3.2 transitively, which is the patched version)
- astro 6.0.6 -> 6.2.2 (#44)
- @tailwindcss/vite 4.2.2 -> 4.2.4
- smol-toml: lockfile bump to 1.6.1 (#28)
- postcss: lockfile bump to 8.5.14 (#48)
- picomatch: lockfile bumps to 2.3.2 + 4.0.4 (#29 #30 #39 #40)
- yaml is now omitted entirely (it was an optional vite peer)

Verified: pnpm build succeeds; no @tailwindcss/vite peer-dep warnings.