Disable weather by default

Details

Weather (seasonal canvas + GPU snow) was on unless localStorage.weather was
explicitly 'off'. Flip the default to off: weather is enabled only when
localStorage.weather === 'on' (any other value, including unset, is off).
- seasonal-background.ts / snow-gl.ts: default reads now require 'on'.
- v2.html: the weather toggle button starts in its off state (weather-off
  class, aria-pressed=false, "Turn on weather animation") so there's no flash
  of the on-state before the script syncs.
- CLAUDE.md: weather default note updated.
The always-on mesh grid is unaffected. Verified offline (desktop + mobile,
dark + light): a fresh load renders no weather (season-bg opacity 0, mesh 1);
clicking the toggle turns it on and persists 'on'; stored 'on'/'off' prefs are
honored; links/CV viewer unaffected.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pn8V4h9YWbjYzdSrDiLiVL

Files changed (4)