fix(selfhost): stop NEXT_PUBLIC_* flags being constant-folded out of the Docker build (#1656)

The image is built once with sentinel values
(ENV NEXT_PUBLIC_SELF_HOSTED=__NEXT_PUBLIC_SELF_HOSTED__) that
docker-entrypoint.sh seds into .next at container start. Comparing a flag in
place defeats that: the bundler inlines the sentinel, the minifier folds
"__NEXT_PUBLIC_SELF_HOSTED__" === 'true' to false and eliminates the branch, so
both the variable name and the sentinel disappear and sed has nothing left to
replace. The flag is then permanently false whatever the operator configures.

Diagnosed against a running self-hosted instance: the compiled gate read

  function r(){return"true"!==process.env.FORCE_PAYWALL
               &&"true"===process.env.DISABLE_PAYWALL}

with the isSelfHosted() branch gone. The un-prefixed FORCE_PAYWALL /
DISABLE_PAYWALL survived precisely because they are never inlined, and
NODE_ENV === 'development' was folded away by the same mechanism. The one
place the flag still worked, getSessionTimeoutConfig(env = process.env), reads
it off a parameter the bundler cannot fold.

Consequence: every Docker self-host ran with the entitlement paywall live, so
ai, bank_sync, skatteverket and email_send went dark 30 days after company
creation when the seeded trial grants expired. Nothing surfaced it, because
dev and the Vercel build both have real env values and never reproduce it.
Analytics, forced MFA, BankID and the hosted upload ceiling read the same flag
and were wrong in the same direction.

Flags are now read as values through lib/env/public-flags, which keeps the
sentinel in the output as a live string literal and defers the comparison to
runtime. flagEnabled uses a Set lookup rather than ===, which a minifier could
fold if it ever inlined the helper.

Guarded twice, because the source fix alone would not have caught this:
- check:guards folded-public-flag fails any in-place NEXT_PUBLIC_* comparison
  (AST, no baseline, verified to fire on a probe file);
- docker-publish asserts the sentinels survive the built image, which is the
  only artifact where the failure is observable.

npm test 14999 passed, npm run lint 0 errors, npm run check:guards clean.

Signed-off-by: Bjorn Bergenheim <29535152+bjornbergenheim@users.noreply.github.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>

DECISIONS.md

@@ -1051,6 +1051,7 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-08-17] 77xx nedskrivningar split per official BAS kopplingstabell in BOTH k2-mapper and ink2-engine (fältkod 7515: 7700-7739, 7750-7789, 7800-7899; 7516: 774x, 779x): agent feedback 2026-07-07 reported the K2 side; the INK2R side and the swedish-sru-filing reference table had the same whole-77xx-to-7516 error, verified against bas.se INK2_P1_intervall-240118.pdf before overriding the skill reference. NE-bilaga mappings deliberately untouched (NE has no separate omsättningstillgångar line).
 [2026-08-17] MCP feedback loop = local /loop-feedback-triage appending dev_docs/mcp_feedback_digest.md + small PRs, NOT a GitHub-issue digest or Resend email: closes the loops.md backlog item blocked since 07-09 on a "channel decision". Issues stay founder-authorised; the digest is the read surface. gnubok_feedback reply copy no longer promises weekly aggregation (it was never true); tool advertised in server instructions + agent briefing (feedback_channel), where it was previously discoverable only by scanning tools/list.
 [2026-08-17] Non-IBAN foreign payment accounts (USD/GBP): added generic bank_code + foreign_account_number to InvoicePaymentAccount (JSONB, no migration) instead of per-country fields (routing_number, sort_code, bsb); rule = IBAN OR (bank_code + foreign_account_number + BIC), only for NON_IBAN_CURRENCIES, label per currency. Chosen over a field per country: the Currency union only carries USD/GBP among non-IBAN systems, and one generic pair keeps the PDF/settings/schema surface small; extend NON_IBAN_CURRENCIES + bankCodeLabelKey when AUD/CAD land. Agent feedback 2026-08-03.
+[2026-08-18] NEXT_PUBLIC_* boolean flags are read as VALUES via lib/env/public-flags (flagEnabled/isSelfHosted), never compared in place: `process.env.NEXT_PUBLIC_SELF_HOSTED === 'true'` is constant-folded against the Docker sentinel at build time and dead-code-eliminated, erasing the sentinel docker-entrypoint.sh needs, so every Docker self-host silently ran with the entitlement paywall live (ai/bank_sync/skatteverket/email_send dying 30 days after company creation). flagEnabled uses a Set lookup rather than `===` because a minifier can fold the latter. Guarded twice: check:guards folded-public-flag (source, every PR) and a docker-publish step asserting the sentinels survive the built image (artifact, the only place the failure is observable: dev and Vercel both have real env values).
 
 [2026-08-18] Swish QR fix (RUT/ROT) scoped to buildSwishQrDataUrl only, preview-pdf left as-is: previewInvoice carries no deduction fields at all, so the editor preview is internally consistent (its QR matches its own totals block) but ignores ROT/RUT entirely; that is a separate display gap to file as its own issue rather than widening this money-math diff.
 [2026-08-18] Shopify webshop_orders port: vat_breakdown is reconstructed from the ORDER-LEVEL taxLines (net = tax / rate, remainder as a 0%-bucket, refuse on missing rates or overshoot) instead of summing line items like the WooCommerce sync: Shopify's discountedTotalSet excludes cart-level discount allocations and lineItems is a paginated connection, so part-summing can silently produce a wrong per-rate net, while tax-per-rate and the charged total are authoritative order-level facts. Refund VAT is always prorated from the parent's mix (Shopify's Refund object exposes no per-rate tax without paging refundLineItems per refund).