fix: review round 7 — fresh-eyes audit fixes (6 agents) + full test suites for every backend change

Fresh-eyes review round with 6 independent agents (money-safety, concurrency,
Square wire parity, security, frontend flow, testing-gaps). Every finding was
independently verified against the code before fixing. All backend changes
now carry full test suites (10+ new tests, each verified to FAIL without its
guard). All 20 packages green, race detector clean.

Money-safety:
- Gift-card purchase refunds no longer create money: manual refunds of a
  no-booking (gift-card purchase) payment are rejected with a clear message
  in the direct handler AND never re-issued by the sweep-resume path
  (processManualPaymentGroup skips them; reconcile-then-fail, no re-issue).
- BuyGiftCard no-client-key fallback: derived deterministically under the
  advisory lock (pending-row reuse fixes lost-response double-charge;
  completed-row sequence advance preserves distinct-purchase collapse fix).
- Terminal completion is never unrecorded: activeTerminalCheckoutID now calls
  recordUntrackedTerminalPayment when a provisional (tmp-) checkout is found
  COMPLETED at Square (previously only marked the row COMPLETED — a lost poll
  left the payment invisible and unrefundable).
- Sweep: provisional tmp- checkout rows are resolved against Square first
  (COMPLETED → record; live → keep guard; NOT_FOUND/CANCELED → fail;
  ambiguous → leave pending) instead of blind-failing a possibly-live
  checkout. recordUntrackedTerminalPayment re-checks the booking status
  (FOR UPDATE) and refuses to record on a cancelled booking, inserting a
  critical_payment_log admin notification instead. Till-sale post-charge
  UPDATE now requires status='pending' (no resurrection of a clawed-back sale).

Frontend (Svelte 5):
- UserPaymentModal keeps CardSelection mounted through processing (bind:this
  ref + Square iframe survive the loyalty/tokenize awaits) — new-card
  payments work again.
- BookingFlow clears the cached nonce/verification pair on any failure (retry
  re-tokenizes fresh; idempotency key retained for dedup); 409 'already paid'
  refetches the booking and reconciles depositPaid so the confirmation gate
  opens; Back button disabled during processing.
- Synchronous double-submit guards on buyGiftCard/redeemGiftCard/submitTip.

Square wire parity (mock vs real):
- processing_fee sign unified (negated at paymentFromSquare; mock agrees).
- SimulateSourceUsed (SOURCE_USED, 400) matches real CreateCard.
- GetCardsOnFile excludes disabled cards (matches ListCards).
- ForcePaymentStatus toggle + tests prove the charge path can't be status-blind.
- CreateCheckout rejects empty device_id (env fallback SQUARE_TERMINAL_DEVICE_ID);
  completed terminal checkout's payment resolvable by id.

Security:
- 2FA attempt-map data race fixed: lastAt is atomic.Int64 (nanos) — eviction
  scan reads race-free; concurrent verify+evict tests under -race.
- Backend refuses to start on weak/placeholder JWT_SECRET_KEY (<32 chars or
  known public placeholders) with openssl rand -hex 32 guidance.
- Dockerfile no longer COPYs .env (secrets injected via compose env_file).
- SabreDAV requires DAV_ADMIN_PASSWORD (no admin/admin default); compose
  fails at config time when missing.

Testing gaps closed (each verified to FAIL without its guard):
- refunded-dedup 409 (CreateBookingPayment), keyed sweep past-retention
  blind-fail, reconcile status-switch (CANCELED/FAILED/APPROVED/PENDING/unknown
  in both by-key and by-id paths), resolveChargeSource Square-failure branches,
  structured 500 / CARD_DECLINED / cancelled-context E2E (row stays pending),
  deriveBookingPaymentIdempotencyKey >45-char truncation, webhook
  findPaymentByDisputeID fallback, clawbackOneTillSale non-gift-card branch,
  dispute.evidence / terminal.checkout dispatch.

Infra:
- local-dev-2.sh fails loudly on port-5432 squatters / docker compose failures
  (previously died silently under ERR_EXIT with hidden output).
- Test harness defaults SQUARE_TERMINAL_DEVICE_ID; money_safety_fixes_test.go
  gained the missing build tag.

Verification: go test -tags test,dev -count=1 -parallel 8 ./... (20/20 ok),
-race clean on 2FA + payments money paths, go build ./... + -tags dev, go vet
clean, svelte-check 0 errors, env-docs gate OK (36 vars), docker compose
config valid.

local-dev-2.sh

@@ -44,8 +44,32 @@ fi
 
 # --- 3. Database Reset ---
 log_step "Resetting PostgreSQL..."
-docker compose down -v postgres > /dev/null 2>&1
-docker compose up postgres -d > /dev/null 2>&1
+# Host port 5432 must be free: the container maps 5432:5432, so a squatter
+# (e.g. a leftover manual postgres) makes the port bind fail. Under ERR_EXIT
+# with hidden output that failure used to kill the script silently.
+if command -v ss > /dev/null 2>&1 && ss -tln 2>/dev/null | grep -q ":5432 "; then
+  log_error "Port 5432 is already in use. The postgres container cannot bind it."
+  log_error "Something else is listening on 5432:"
+  ss -tlnp 2>/dev/null | grep ":5432 "
+  log_error "Stop the process holding 5432 (e.g. a manually-started postgres), then re-run."
+  exit 1
+fi
+if ! docker compose down -v postgres > /tmp/opencode/pg-down.log 2>&1; then
+  log_error "Failed to stop old postgres container. See /tmp/opencode/pg-down.log"
+  exit 1
+fi
+if ! docker compose up postgres -d > /tmp/opencode/pg-up.log 2>&1; then
+  log_error "Failed to start postgres container. See /tmp/opencode/pg-up.log"
+  exit 1
+fi
+# ERR_EXIT cannot catch a container that is 'Up' but lost its host port mapping
+# (docker can report success while the bind silently fails). Verify the map.
+if ! docker port postgres 5432 > /dev/null 2>&1; then
+  log_error "postgres container started but is NOT mapped to host port 5432."
+  docker logs postgres 2>&1 | tail -5
+  log_error "Free host port 5432 (see ss output above) and re-run."
+  exit 1
+fi
 log_success "PostgreSQL reset complete"
 
 # --- 3a. Wait for PostgreSQL to be ready ---