BOLT-1191: Shareable chart views via URL-encoded state

Generalized useChartViewUrlState hook + wire SiteEnergyCharts as reference consumer. Encodes after/before/windowSize/hidden/chartZoom/expanded in URL so sharing /sites/abc/energy?... reproduces the exact view. Extends RESERVED_PARAM_KEYS in apps/dashboard/lib/filtering/url-params.ts. v2 rollout to ~17 other ChartContainer consumers is separate follow-up issues. Linear: https://linear.app/texture/issue/BOLT-1191. Queued — do NOT start until #11762 (BOLT-1160 Phase 3) merges and Richie gives the go-ahead.