chore: Cat-C typo and naming polish from W10 dead-code probe

W10's dead-code candidates report (§C2) flagged a half-quoted reference
inside `src/app/api/insights/targets/route.ts:807`. The comment claimed
the AI prompts lived at `src/lib/insights/prompts/{base-system,
general-status}.ts`, but those files actually sit under
`src/lib/ai/prompts/` and the brace-expansion abbreviation was both
wrong-pathed and easy to misread as a stray-brace typo.

The comment is rewritten in full path form so future readers can grep
the referenced files directly and so the source citation matches the
real location.

Verification:
  pnpm typecheck                         → clean
  pnpm lint                              → clean
  grep -rn 'general-status}' src         → zero hits

src/app/api/insights/targets/route.ts

@@ -803,9 +803,10 @@ export const GET = apiHandler(async () => {
       // WHO publishes activity *time* (150–300 min/wk moderate),
       // not a step quota. The closest peer-reviewed dose-response
       // for the 8 000–15 000 band is Saint-Maurice JAMA 2020. The
-      // AI prompts at src/lib/insights/prompts/{base-system,
-      // general-status}.ts already enforce this attribution; this
-      // surface label was the last "WHO" mislabel in the codebase.
+      // AI prompts at src/lib/ai/prompts/base-system.ts and
+      // src/lib/ai/prompts/general-status.ts already enforce this
+      // attribution; this surface label was the last "WHO" mislabel
+      // in the codebase.
       source: "Saint-Maurice JAMA 2020",
       ...consistency,
     });