Add HDSSettings singleton and unit-aware formatting (Plan 11 Phase 1)

- HDSSettings: hook to Application/Connection, typed get/set, browser
  defaults fallback, 1 event per setting storage model
- formatEventDate: locale-aware date formatting (DD.MM.YYYY etc.)
- eventToShortText: unit conversion using model conversions (mass, length, temperature)
- HDSModel-Conversions: reads conversion factors from data model

Author: perki

js/HDSModel/HDSModel-Conversions.d.ts

@@ -0,0 +1,28 @@
+import { HDSModel } from './HDSModel';
+import type { UnitSystem } from '../settings/HDSSettings';
+export interface ConversionResult {
+    value: number;
+    targetEventType: string;
+}
+/**
+ * Conversions — Extension of HDSModel
+ *
+ * Reads conversion definitions from the model (pack.json → conversions).
+ * Each category (mass, length, temperature) defines:
+ *   - metric/imperial unit names
+ *   - factors: { from: { to: number | [factor, offset] } }
+ */
+export declare class HDSModelConversions {
+    #private;
+    constructor(model: HDSModel);
+    /**
+     * Convert a numeric value from one event type to the preferred unit system.
+     * Returns null if no conversion is needed or available.
+     *
+     * @param eventType - e.g. "mass/kg"
+     * @param value - the numeric value to convert
+     * @param targetSystem - "metric" or "imperial"
+     */
+    convert(eventType: string, value: number, targetSystem: UnitSystem): ConversionResult | null;
+}
+//# sourceMappingURL=HDSModel-Conversions.d.ts.map

js/HDSModel/HDSModel-Conversions.d.ts.map

@@ -3,6 +3,7 @@ import { HDSModelAuthorizations } from './HDSModel-Authorizations';
 import { HDSModelItemsDefs } from './HDSModel-ItemsDefs';
 import { HDSModelEventTypes } from './HDSModel-EventTypes';
 import { HDSModelDatasources } from './HDSModel-Datasources';
+import { HDSModelConversions } from './HDSModel-Conversions';
 export declare class HDSModel {
     #private;
     /**
@@ -34,5 +35,6 @@ export declare class HDSModel {
     get authorizations(): HDSModelAuthorizations;
     get eventTypes(): HDSModelEventTypes;
     get datasources(): HDSModelDatasources;
+    get conversions(): HDSModelConversions;
 }
 //# sourceMappingURL=HDSModel.d.ts.map

js/HDSModel/HDSModel-Conversions.js

@@ -1,6 +1,6 @@
 /**
  * Format a Unix timestamp (seconds) as a date string.
- * Centralized here so we can later hook into user locale/format preferences.
+ * Uses HDSSettings dateFormat + timezone when available, otherwise ISO date.
  */
 export declare function formatEventDate(timeSec: number): string;
 /**