scripts/taler-landing: full-scan bank collector with GOA alt units

Add a host-side Python collector that lists every bank account, pages
through all ledger rows, and emits stats.json with amount_alt fields
(Kilo/Mega/Peta-GOA) so large ladder withdrawals fit on the landing tiles.

scripts/taler-landing/README.md

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+# taler-landing — central stats (hernani user systemd)
+
+Public landing numbers on
+
+- https://bank.hacktivism.ch/intro/ → `stats.json`
+- https://exchange.hacktivism.ch/intro/ → `stats.json`
+- https://taler.hacktivism.ch/intro/ → `stats.json`
+
+are produced by **one host process** as user **`hernani`**, not by three unrelated in-container crons.
+
+## Why host / user systemd
+
+| Concern | Approach |
+|--------|----------|
+| **All accounts / all money** | Python full scan + tx pagination (not capped at 80 accounts) |
+| **High ladder GOA** | `amount_alt` / UI alt units (Kilo-/Mega-/Peta-GOA) — tiles stay short |
+| **No root cron** | `systemctl --user` as hernani + `loginctl enable-linger` |
+| **Failure safety** | failed run only updates `stats-run.json`; last good `stats.json` stays |
+
+## Install (on koopa as hernani)
+
+```bash
+cd ~/src/koopa/koopa-admin-log
+./scripts/taler-landing/install-landing-stats-host.sh
+
+# timer without login session:
+sudo loginctl enable-linger hernani
+
+# run once:
+systemctl --user start taler-landing-stats.service
+journalctl --user -u taler-landing-stats.service -n 50 --no-pager
+systemctl --user list-timers 'taler-landing-stats*'
+```
+
+Units:
+
+- `configs/systemd/user/taler-landing-stats.service` — oneshot collector  
+- `configs/systemd/user/taler-landing-stats.timer` — every **2 minutes** after boot  
+
+Installed paths:
+
+| Path | Role |
+|------|------|
+| `~/.local/bin/collect-landing-stats.sh` | orchestrator |
+| `~/.local/lib/taler-landing/*.py` | bank scan + alt enrich |
+| `~/.local/state/taler-landing-stats/` | logs |
+| `~/.config/systemd/user/taler-landing-stats.*` | user units |
+
+## What the collector does
+
+1. **Bank** — `collect_bank_stats.py`  
+   - admin token → list **all** accounts  
+   - for each account (except `SCAN_SKIP`, default **`exchange`**) page through **all** transactions  
+   - sum credits / Taler withdraws / other debits  
+   - emit `amount` + `amount_alt` / `amount_full`  
+   - `podman cp` → `taler-hacktivism-bank:/var/www/bank-landing/stats.json`
+
+2. **Exchange** — run `landing-stats-exchange.sh` inside exchange container, then **enrich** alt fields on the host and write back.
+
+3. **Merchant** — same for merchant container.
+
+`exchange` is skipped in the bank **flow** scan so the same GOA is not counted once as customer withdraw and again as exchange credit. **Admin**, **explorer**, and every auto-account are included.
+
+## Secrets
+
+Preferred order:
+
+1. `~/src/koopa/koopa-admin-secrets/koopa/host-root/taler-bank/bank-admin-password.txt`  
+2. `~/.config/taler-landing/bank-*-password.txt`  
+3. `podman exec taler-hacktivism-bank cat /root/bank-admin-password.txt`
+
+Explorer password optional (shared-pool balance).
+
+## Env overrides
+
+| Env | Default | Meaning |
+|-----|---------|---------|
+| `BANK_URL` | `http://127.0.0.1:9012` | libeufin loopback |
+| `SCAN_SKIP` | `exchange` | usernames excluded from flow |
+| `TX_PAGE` | `500` | transactions page size |
+| `MAX_TX_PAGES` | `0` | `0` = unlimited pages / account |
+| `ACCOUNTS_DELTA` | `-10000` | account list window |
+| `ADMIN_LOG` | `%h/src/koopa/koopa-admin-log` | refresh in-container scripts |
+
+## UI alt names
+
+`configs/shared/goa-amount.js` formats large amounts as e.g. `1.23 Mega-GOA` (tooltip = full `GOA:…`). Landings load it as `/intro/goa-amount.js` (deploy via `deploy-landings.sh`).
+
+## Legacy in-container bank cron
+
+`scripts/taler-bank/landing-stats.sh` remains a **fallback** inside the bank container. Once the hernani timer is healthy, disable the old in-container minutely cron to avoid races:
+
+```bash
+podman exec taler-hacktivism-bank crontab -l   # inspect
+# remove landing-stats.sh line if present
+```
+
+## Manual run
+
+```bash
+~/.local/bin/collect-landing-stats.sh
+# or from checkout:
+./scripts/taler-landing/collect-landing-stats.sh
+
+curl -sS https://bank.hacktivism.ch/intro/stats.json | python3 -m json.tool | head
+```