Add quote-aware price label with reload and realtime multi-chart cards

[Bobagi]

Motivation

• Make every displayed monetary value explicitly show the quote currency, improve the visibility of the "Current price" label, and allow manual refresh without changing existing layout or fetch logic.
• Provide real-time, independent chart cards (multiple at once) so users can add/remove charts and observe sliding-window live updates with proper axis behavior and tooltips.
• Supply a minimal backend endpoint to initialize charts with historical klines by period while keeping polling isolated per card and avoiding duplicate intervals.

Description

• UI: updated templates/index.html to strengthen the current-price label styling, add a reload button next to the label in all symbol dropdowns, and replace the plain-muted price text with formatted, quote-aware price text.
• UI: added a new full-width "Real-time crypto charts" section with an Add (+) modal and autocomplete flow, plus chartDashboard() and chartCard() Alpine components implementing per-card state, a period selector (1Y/3M/1M/1W/1D), a fixed-size sliding window (N=80), 5s polling, dynamic y-axis init/expansion, highlighted current point, line history, non-flickering tooltip, always-visible Y min/max indicators, floating price indicator line/label, and improved X-axis tick formatting dependent on period.
• JS utilities: added detectQuoteCurrency(), formatPriceByQuote() and formatTimestampByPeriod() helpers and updated symbolDropdown() to add reloadPrice() and to format prices with explicit quote currency (including BRL locale formatting) while reusing the existing /binance/price endpoint (force-reload via timestamp query param).
• Backend: extended internal/service/binance_price_service.go with BinanceKlinePoint and GetKlineClosePrices(...) to fetch and parse close prices from Binance klines; added a new /binance/klines route and handleBinanceKlines in internal/httpserver/server.go and a BinanceKlinesResponse struct to return historical points by the selected period/interval mapping.
• Safety/cleanup: per-card polling uses setInterval and is cleared on card removal to avoid duplicate polling or leaks, and chart initialization reuses the existing price fetch for updates.

Testing

• Ran code formatting with gofmt -w internal/service/binance_price_service.go internal/httpserver/server.go successfully.
• Built the project with go build ./... which completed successfully in the CI-like environment used here.
• Attempted to run the server with go run ./cmd/server but the process exited early due to an unreachable database host in this environment (DNS for db not resolvable), so end-to-end UI runtime verification (browser smoke) could not be executed here.

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Codex Task