feat(dimensions): PR10 advanced — custom dimensions, hierarchy, account rules, commit enforcement (#886)

* feat(dimensions): PR10 advanced — custom dimensions, hierarchy, account rules, commit enforcement

The final rung of the dimensions ladder
(dev_docs/dimensions_implementation_plan.md §7 row 10):

- custom dimensions: POST /api/dimensions creates registry dims (next free
  SIE number >= 20 when omitted; explicit numbers allowed — SIE import
  already mints reserved ones); register gets a 'Ny dimension' dialog with
  a quiet Avancerat disclosure for the #UNDERDIM parent; GET now carries
  parent_sie_dim_no (the column + SIE round-trip existed since PR1/PR5 —
  this exposes it)
- account_dimension_rules (migration 20260703120000): one rule per
  (account, dimension) — required / default / fixed, per-rule is_active,
  company-scoped RLS, composite FK to the registry, value-presence CHECK
- enforcement, opt-in BY CONSTRUCTION (zero rules = engine byte-identical;
  deliberately NO settings toggle — a rule that exists but is ignored is
  worse than either extreme): default/fixed apply onto line bags at draft
  creation (fixed overwrites, default fills); required asserts at
  commitEntry with a Swedish MANDATORY_DIMENSION_MISSING naming every
  account + dimension; the bulk-book route runs the same policy before its
  RPC; storno/correction paths never pass through commitEntry so history
  always reverses regardless of policy; rule fetches fail open incl.
  thrown exceptions
- chart of accounts: per-account Dimensionsregler section in
  EditAccountDialog (Krävs/Förval/Låst, value picker, pause switch),
  gated on the existing dimensions toggle, quiet when empty
- pickers: LineDimensionFields is registry-driven (one combobox per active
  dimension, cached fetch, hardcoded 1/6 fallback) — every existing mount
  lights up custom dims with zero changes
- agent briefing: per-dimension required_on_accounts/default_on_accounts
  so agents self-correct instead of bouncing off the policy error
- rules CRUD API with existence/active/company validation and qualified
  DTO ids; firm_id FK deferred until the firms table lands (per plan)

39 new tests (pure-fn rules, engine enforcement, both new API surfaces,
pg-real RLS/CHECK/cascade suite); full suite 6,791 green; migration
replayed on a fresh container.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix: renumber migration to 20260703200000 — version collision with prod

The concurrent session shipped pending_operations_add_link_document_to_voucher
as 20260703120000 today; the Supabase preview branch (cloned from prod)
rejected the duplicate version key.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix: review round — auto-pick retry on collision, fail-open warnings, query schema

- POST /api/dimensions retries once past a concurrent number claim when the
  number was auto-picked (explicit choices still 409)
- every fail-open skip of the dimension-rules policy now logs a structured
  warning (engine draft/commit paths + bulk-book) — deliberate fail-open,
  but observable
- GET /api/dimensions/rules validates its query through
  ListDimensionRulesQuerySchema instead of an inline regex

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/bookkeeping/errors.ts

@@ -1,5 +1,5 @@
 import { NextResponse } from 'next/server'
-import { DimensionValidationError } from './dimension-errors'
+import { DimensionValidationError, MandatoryDimensionMissingError } from './dimension-errors'
 
 // ============================================================================
 // Dimension validation error — class lives in ./dimension-errors.ts (pure
@@ -14,10 +14,15 @@ export {
   formatDimensionValidationIssue,
   formatDimensionValidationIssues,
   isDimensionValidationError,
+  MANDATORY_DIMENSION_MISSING,
+  MandatoryDimensionMissingError,
+  formatMandatoryDimensionViolation,
+  isMandatoryDimensionMissingError,
 } from './dimension-errors'
 export type {
   DimensionValidationIssue,
   DimensionValidationReason,
+  MandatoryDimensionViolation,
 } from './dimension-errors'
 
 // ============================================================================
@@ -331,7 +336,8 @@ export function isBookkeepingError(err: unknown): boolean {
     err instanceof NoOpenPeriodForDateError ||
     err instanceof TargetPeriodClosedError ||
     err instanceof TargetPeriodLockedError ||
-    err instanceof DimensionValidationError
+    err instanceof DimensionValidationError ||
+    err instanceof MandatoryDimensionMissingError
   )
 }
 
@@ -574,6 +580,22 @@ export function bookkeepingErrorResponse(err: unknown): NextResponse | null {
     )
   }
 
+  if (err instanceof MandatoryDimensionMissingError) {
+    // Policy rejection at commit (dimensions PR10): the message names every
+    // account + required dimension so a user or agent self-corrects in one
+    // pass; details.violations is the machine-readable list.
+    return NextResponse.json(
+      {
+        error: {
+          code: err.code,
+          message: err.message,
+          details: { violations: err.violations },
+        },
+      },
+      { status: 400 }
+    )
+  }
+
   if (err instanceof BookkeepingDatabaseError) {
     return NextResponse.json(
       {