fix: a hand-assigned award reference no longer loses to the matcher

Reported on the DARC DOK award, with DL2FDM: a German address matches two or
three DOKs, the operator deletes the wrong ones and assigns the right one, and
the next recompute puts the wrong ones straight back.

The manual reference was APPENDED to what the matcher found. Storage already
kept exactly one manual entry per award — setOverrideRef drops the previous one
— so it was an override everywhere except at the one place it mattered. The
operator was arguing with the matcher and could not win.

It now replaces. The trace records what was superseded, so a corrected QSO can
still be explained rather than being merely different. A QSO with no correction
keeps every automatic reference, which the test also pins: an override must not
quietly disable matching for everyone else.

This does not address the over-matching itself — an address containing "Berlin
Mitte, 10115 Berlin" genuinely matches two DOK descriptions. That is the next
question, and a separate one.

frontend/wailsjs/go/models.ts

@@ -461,6 +461,7 @@ export namespace award {
 	    ref_count: number;
 	    steps: Step[];
 	    manual?: string[];
+	    superseded?: string[];
 	    result: string[];
 	
 	    static createFrom(source: any = {}) {
@@ -476,6 +477,7 @@ export namespace award {
 	        this.ref_count = source["ref_count"];
 	        this.steps = this.convertValues(source["steps"], Step);
 	        this.manual = source["manual"];
+	        this.superseded = source["superseded"];
 	        this.result = source["result"];
 	    }