Add real-time chart cards and explicit price labels with reload

[Bobagi]

Motivation

• Make the current-price UI explicit about which quote currency is shown and make it more visible to avoid ambiguity (e.g. BTCBRL was showing a value in BRL but not indicating the unit).
• Provide a convenient reload action for current price lookups so users can refresh the value on demand.
• Add a lightweight, non-invasive real-time charting experience on the dashboard so multiple independent charts can be added and monitored simultaneously.
• Back charts with historical klines from Binance to compute per-period min/max and initialize the chart window.

Description

• Enhanced templates/index.html with a visible current-price-panel, a reload button and improved formatting of price labels using helpers like determineQuoteAssetFromSymbol and buildCurrentPriceLabel so every Current price shows the quote asset (BRL, USDT, BTC, etc.).
• Reworked the existing symbolDropdown Alpine component to expose currentPriceLabel and a refreshPrice() action, replacing the old currentPriceText behavior and adding a small loading indicator.
• Implemented a new realTimeChartDashboard Alpine component in templates/index.html that provides a full-width “Add chart” card and allows creating multiple chart cards that poll every 5 seconds, maintain a sliding window of points (configurable window size), render a single highlighted latest point plus the history line, and let each card change period (1Y, 3M, 1M, 1W, 1D).
• Added internal/service/binance_historical_price_service.go, a BinanceHistoricalPriceService to fetch klines and compute minimum/maximum for a period, exposed a new HTTP endpoint /binance/history and extended server wiring (internal/httpserver/server.go, cmd/server/main.go) and NewServer to include and update the historical-price service.

Testing

• No automated tests or builds were executed as per the modification instructions.
• A Playwright screenshot attempt failed due to a missing file context in the browser container (non-blocking for the change).
• Manual runtime verification is suggested: start the server and visit the dashboard to validate Current price (BRL) labels, the reload button, and add/remove real-time chart cards that update every 5 seconds.
• All modified files: templates/index.html, internal/service/binance_historical_price_service.go, internal/httpserver/server.go, and cmd/server/main.go were compiled into this change set.

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Codex Task