ci(verify): open promotion PRs against TechAPI develop

TechAPI has adopted git-flow (GetTechAPI/TechAPI#141): main is the released
state that publishes the site, develop is where integration lands. The
promotion bot writes data, so it belongs on develop.

Checks out TechAPI at develop as well as targeting it — cutting the bot branch
from main would place it behind whatever is already integrated, and the
resulting PR would drag those commits along.

Author: Seungpyo1007

.github/workflows/verify-network.yml

@@ -45,6 +45,10 @@ jobs:
         with:
           repository: GetTechAPI/TechAPI
           path: TechAPI
+          # TechAPI follows git-flow: promotions are integration work, so branch
+          # from develop and open the PR there. Cutting from main would put the
+          # bot branch behind whatever is already integrated.
+          ref: develop
           fetch-depth: 0
           token: ${{ secrets.TECHENGINEBOT_TOKEN || secrets.TECHAPI_TOKEN || secrets.GITHUB_TOKEN }}
 
@@ -121,6 +125,6 @@ jobs:
           Auto-promotions from the verification layer (green+live-source or crossref-confirm).
           Each flip is verified:false->true only; see data/_verify/ledger.jsonl. Refs #1"
           git push origin "$branch"
-          gh pr create --repo GetTechAPI/TechAPI --base main --head "$branch" \
+          gh pr create --repo GetTechAPI/TechAPI --base develop --head "$branch" \
             --title "data(verify): verified promotions ($(date -u +%Y-%m-%d))" \
             --body "Automated verified promotions from \`app.verify promote\` (run in TechEngine). Each change flips only the \`verified\` flag; structural validator passed and diff scope guarded. Review before merge. Refs #1"