Normalize currency codes, improve auth/connectivity handling, add options & UI fixes

[GuvHas]

Motivation

• Move currency handling to ISO-style codes and provide consistent symbols and normalization to avoid legacy-symbol ambiguity.
• Improve detection and handling of authentication and transient connectivity errors from the third-party cellartracker library to present accurate HA config flow feedback and coordinator behavior.
• Tighten options validation for scan interval and harden the UI/API endpoints and embedded web UI for safer token handling and display of currency symbols.

Description

• Replace legacy currency symbols with ISO-like codes and add CURRENCY_SYMBOLS, LEGACY_CURRENCY_MAP, DEFAULT_SCAN_INTERVAL, MIN_SCAN_INTERVAL, and normalize_currency in const.py and update defaults accordingly.
• Update cellar_data.py to use CONF_USERNAME, CONF_PASSWORD, and CONF_SCAN_INTERVAL, add _is_auth_error/_is_connectivity_error helpers, raise ConfigEntryAuthFailed for auth failures, log connectivity issues, and set always_update=False on the DataUpdateCoordinator.
• Improve config_flow.py to normalize currency input, validate credentials using the cellartracker library with granular error mapping (auth, cannot_connect, unknown), and enforce minimum scan interval constraints in the UI.
• Update sensor.py to normalize the configured currency for the monetary sensor and mark the inventory status sensor with EntityCategory.DIAGNOSTIC.
• Enhance REST views in views.py to expose currency_symbol alongside currency from /api/cellartracker/settings using CURRENCY_SYMBOLS.
• Harden the embedded web UI www/cellar.html with improved token extraction (supporting ct_token), same-origin credentials, safer fetch error messaging, normalized settings usage for currency_symbol, rel="noopener noreferrer" on links, and improved search/filter event handling.
• Bump package metadata version in hacs.json to 0.0.11.

Testing

• No automated tests were added or executed as part of this change.

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Codex Task