Ads: 4 of 12 generated spots share the prompt's example number 555-0142 — the 3B model copies the example

[genwave-radio]

What airs

Demo, 12 ready spots on 5.6.2: #11 Halvorsen, #14 Hollins Ferry, #15 Bramblewood, #16 Millbrook all say 555-0142 (#7 0115, #8 0198, #9 0158, #10 0211). "Just checked 4 ads, they all have the same fake phone number."

Why

src/GenWave.Tts/AdScriptPromptBuilder.cs:77-79: "Any phone number spoken must use the fictional 555 exchange, for example 555-0142." llama3.2:3b copies literal examples — the same class as #696's TAG placeholder.

Fix

Give each brand its own number and tell the model exactly what it is, instead of an example:

• deterministic per brand: 555-01xx from a stable hash of the brand (555-0100…0199 is the reserved fictional block), so the same brand keeps the same number across regenerations — a campaign sounds like a campaign;
• prompt: "If the spot gives a phone number, it is 555-0173, said once." — no generic example;
• hygiene/validator: any other 555 number in the reply is rewritten to the brand's number (PhoneShapeCheck already finds them);
• rider: an optional phone field on the brief (owner + pack) overrides the derived one — same plumbing shape as Ads: a brief's structure hint is stored and displayed but never reaches the LLM prompt #693's structure hint.

Pairs with #700 (the number has to survive TTS to matter).

Epic: #380