Remove calls to undefined ym()

typeof ym is 'undefined' on production. Clicking the CTA button or the share link executes ym(34795480, 'reachGoal', ...) and throws before the handler finishes. Navigation still happens, but the copy-to-clipboard branch in SharePostLink runs after the throw and never executes.

Extract hardcoded config values tracks moving the counter ID into config; this todo is about the runtime error itself.

Tasks

• Remove the ym() calls from src/lib/CallToAction.svelte and src/lib/SharePostLink.svelte
• If analytics goals are wanted in the bootstrap, add a tiny track(goal) helper in #lib that no-ops when no provider is configured
• Drop the global ym declaration from src/app.d.ts