intake: match merchants on whole words, not substrings

merchantKey("Bigals Pizza") contains "iga", so GROCERY_PATTERN filed a pizza
shop as a grocer and merchantMatches matched it against every IGA on the same
date and total. Short names in a substring list collide with ordinary words,
and the collision reads as a correct classification rather than a bug.

GROCERY_PATTERN is now a word-boundary alternation; merchantMatches asks
whether one name's words appear as a contiguous run inside the other's, which
keeps Coles <-> Coles (Wyndham Vale) and Order - Coles (Wyndham Vale).

Also collapses the third PLATFORM_LABEL copy: order-ingestion's was exported
and read nowhere, order-details.tsx had its own, and the intake one — the only
live copy — was missing `uber`. One map, in intake-rules.

src/lib/order-ingestion.ts

@@ -12,13 +12,6 @@ export const CUTOVER_DATE = "2026-01-09";
  */
 export const DEFAULT_OWNER_ID = 1;
 
-/** Human labels for the platform a receipt came from. */
-export const PLATFORM_LABEL: Record<ParsedOrder["platform"], string> = {
-  doordash: "DoorDash",
-  ubereats: "Uber Eats",
-  uber: "Uber",
-};
-
 /**
  * Transaction description.
  *