K1: card purchases on the server (schema 4, Enable Banking adapter, E-36 to E-44)

Contract (SPEC §14.8): migration 0004_card_purchases.sql (server schema 4, byte-identical
contract and server copies), E-36 to E-44 in contracts/openapi.yaml with the four new error
codes and a 502 response, examples for every card body and error code, the
match_card_purchase vectors (17 cases) with their Python reference in tools/contracts-check.py
(157 checks), web/src/api/schema.d.ts regenerated; web/src/lib/vectors.test.ts lists
match_card_purchase as not ported until K3 ports it (orchestrator's allowance).

Server: src/cards/ with the provider registry (CP-1), the CardSource trait and its
Enable Banking adapter (JWT RS256 kid = application id, /aspsps, /auth, /sessions,
transactions with PSU headers for user-present fetches, CP-14 error mapping, CP-7 mapping),
the windowed fetch (30-day windows newest first, split at the 100-row cap down to a day,
de-duplication by provider_ref, continuation keys, WRONG_TRANSACTIONS_PERIOD ends the walk),
CP-8 matching with the secondary rule, the background poller (06:45, 11:45, 16:45, 21:45,
4 per 24 hours, 2-hour skip, no backlog), the bilingual callback page (E-39), E-36 to E-38
and E-40 to E-44, link clearing in sync push step 7, attempt pruning at 04:00, the card_fetch
log line with aggregates only, KVITT_EB_* configuration. Tests against a local stub
(tests/cards_api/, 34 tests); the real API is never called.

Infra: Pi compose mounts secrets/cards read-only and passes the two application ids;
.env.example keys; dev stack stages infra/secrets/cards/; NPM block with the /cards/callback
gate line and unlogged location (kvitt.conf and README step 4); README "Card purchases".

Pre-commit hook bypassed (--no-verify, orchestrator's decision): the Android fast tests fail
in :domain VectorFilesTest (and the full check in :data ExampleRoundTripTest) because they pin
the contract's vector and example sets; matchCardPurchase and the card DTOs are K2's by design
(contract-first landing; K2 lands next). Server, contracts-check and web gates are green.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

infra/npm/kvitt.conf

@@ -13,6 +13,8 @@ if ($uri ~ "^/\.well-known/acme-challenge/") { set $kvitt_gate 1; }
 # and /apk/, which stay LAN-or-key only.
 if ($uri ~ "^/app(/|$)") { set $kvitt_gate 1; }
 if ($uri = "/invites/accept") { set $kvitt_gate 1; }
+# Card connection (SPEC §9.12, D-163): the bank redirects the user's browser here, without the app key.
+if ($uri = "/cards/callback") { set $kvitt_gate 1; }
 set $kvitt_bearer 0;
 if ($http_authorization ~ "^Bearer ") { set $kvitt_bearer 1; }
 if ($uri ~ "^/(health|setup/|i/|apk/)") { set $kvitt_bearer 0; }
@@ -58,3 +60,14 @@ location ^~ /i/ {
   proxy_set_header X-Real-IP $remote_addr;
   proxy_pass $forward_scheme://$server:$port$request_uri;
 }
+# Card connection callback /cards/callback?code=…&state=… (SPEC §9.12, D-163): the query carries a one-time
+# authorisation code and the attempt's state, so this path is not logged at all, a 502 included.
+location = /cards/callback {
+  access_log off;
+  error_log /dev/null crit;
+  proxy_set_header Host $host;
+  proxy_set_header X-Forwarded-Proto $scheme;
+  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+  proxy_set_header X-Real-IP $remote_addr;
+  proxy_pass $forward_scheme://$server:$port$request_uri;
+}