Implement the Belgian Registered Cash Register (Caisse Enregistreuse Certifiée) v2 specification as required by FPS Finance for certified POS restaurant systems.

The implementation is split into a core module and five bridge modules:

l10n_be_pos_blackbox (main module):
- FDM (Fiscal Data Module) communication layer that signs every fiscal
  event by sending a structured message to the blackbox device and
  receiving a hash + VSC counter in return.
  M110 (sale), M111 (refund), M112 (partial refund), M121 (order),
  M122 (cost-centre change), M123 (pre-bill), M130 (money in/out),
  M131 (drawer open), M140/M141 (work in/out), M150 (invoice),
  M160 (copy), M180/M181 (X/Z turnover report), M182/M183 (user X/Z
  report), UC230 (sale correction).
  M160 (copy), M180/M181 (X/Z turnover report), M182/M183 (user X/Z
  report), UC230 (sale correction).
- Input generator that encodes all line-level fiscal data (PLU hash,
  VAT groups, price rounding, grouping IDs) according to the spec.
- Fiscal receipt template (XML) that renders the blackbox hash,
  VSC counter, POS system identifier, and event sequence number on
  every printed receipt.
- X/Z daily report views with fiscal totals per VAT category.
- Training-mode support: activates the FDM training flag so the
  device does not count test transactions.
- Inspect popup (debug) for examining raw FDM messages.
- Error/warning popup system with traceback messages from the device.
- LocalStorage queue to replay pending mutations after a network
  outage.
- pos_config / pos_session overrides: enforce blackbox constraints
  (only EUR, no rounding, mandatory restaurant mode, etc.),
  manage device pairing, and accumulate per-session fiscal counters.
- Extensive unit-test suite: >6 000 lines covering the input
  generator's grouping-ID logic, price-consistency rules, and every
  mutation type against golden JSON fixtures.
- Browser tour tests (oracle + regression tours).

l10n_be_pos_blackbox_hr:
- Clock-in / clock-out flows for employees trigger M140/M141 work
  in/out mutations; employee INSZ/NISS number is required and stored
  on hr.employee; pos_session accumulates per-employee work records.

l10n_be_pos_blackbox_loyalty:
- Gift-card and discount reward lines are mapped to the correct MPV
  fiscal codes (UC260/UC261); loyalty products are flagged so the
  input generator can calculate their contribution to the signed
  total correctly.

l10n_be_pos_blackbox_self_order:
- Intercepts self-order confirmation on kiosk screens to sign the
  order with the FDM before the confirmation page is shown; adds a
  controller to expose the required blackbox data to the kiosk
  frontend.

l10n_be_pos_blackbox_settle_due:
- Handles the "settle due" payment flow: products used to represent
  deferred payments are flagged and treated as zero-VAT lines in the
  signed message.

l10n_be_pos_blackbox_urban_piper:
- Patches the Urban Piper ticket-screen and pos_store so that online
  orders routed through Urban Piper are also signed before finalisation.

task-id: 5864870

community PR: https://github.com/odoo/odoo/pull/229692