feat: cover seedlings (plantón) in copy + legal, backup cadence, server picker

Beta-tester feedback triage. The data model already had LotType.seedling as
first class; the gaps were copy and UX.

- Seedlings/plantones: broaden landing hero (EN/ES), in-app legal notice, and
  all legal texts (site + docs masters) from seeds-only to "seeds and
  seedlings", with a live-plant phytosanitary/transport caveat. Seeds stay the
  hero — targeted, not a blanket rename.
- Backups: settings line now states the 7-day cadence explicitly; cadence lives
  in AutoBackupService.backupInterval as the single source for text and schedule.
- Community servers: replace the manual wss:// text box with a checklist of the
  known servers (defaults visible/toggleable) plus an "add server" affordance
  with basic validation. No jargon in the UI.

i18n across en/es/pt/fr/de/ast (ja falls back). Tests updated + a new
server-picker widget test.

docs/legal/community-rules.md

@@ -16,8 +16,9 @@ content that can be reported and removed from the servers we operate.
      unless you are authorized;
    - **invasive or protected species** where their exchange is prohibited;
    - anything else that is illegal to share or sell where you or the recipient live.
-3. **Seeds, not anything else.** The market is for seeds and plant reproductive
-   material in the spirit of the app. It is not a general classifieds board.
+3. **Seeds and seedlings, not anything else.** The market is for seeds, seedlings and
+   other plant reproductive material (cuttings, bulbs, tubers) in the spirit of the app.
+   It is not a general classifieds board.
 4. **Respect people.** No harassment, threats, hate, or discrimination — in offers,
    profiles, ratings, or messages.
 5. **No spam or scams.** No repeated postings, misleading offers, phishing, or