absorb whatsapp-bot into the monorepo (was an unregistered nested repo)

whatsapp-bot/ carried its own .git and was recorded in the parent as a gitlink at c7f6738, but no .gitmodules ever existed. Two consequences:

• git add . at the root could never stage anything inside it, so the bridge's changes were silently left out of every commit.
• git clone of this repo produced an EMPTY whatsapp-bot/ with no way to populate it (no registered URL for submodule update --init), so CI cloning the parent got no bridge code at all.

Remove the nested .git, drop the gitlink, and track the files directly. The pre-split history (including CONTRACTS.md, DEPLOY.md, FEASIBILITY.md and the UX prototype, all deleted during the module split) remains at the whatsapp-mvp remote and in temp/whatsapp-bot-history.bundle.

Also fix two .gitignore patterns that only worked at the repo root: gitignore anchors any pattern containing a slash to its own directory, so */node_modules/ and public/tickets/*.pdf did NOT cover whatsapp-bot/. With the nested .git gone those paths became visible to the root .gitignore for the first time; without the ** prefix this commit would have added node_modules/ and the generated ticket PDFs.

Co-Authored-By: Claude noreply@anthropic.com