feat: marjă internă per mechanic — hidden margin on labor

Client sees only Total. Salary is calculated from salary_base = client_price
× (1 − margin/100). Margin never appears in customer-facing surfaces (PDF,
tracking JSON, portal).

Terminology: "marjă internă" — internal profit margin. NOT VAT/TVA. Never
called NDS/TVA anywhere in the code to avoid confusion with real Moldova
tax reporting (Doc 19/1C integration).

== Configuration ==

Fallback chain (in MarginResolver::resolve):
  1. WorkOrder.override_margin_pct — per-Fișă for special contracts/VIP
  2. User.internal_margin_pct — per-mechanic (main setting)
  3. Company.settings.default_internal_margin_pct — tenant default
  4. 0.0 — no margin

Example (mechanic Andrei with 20% margin):
  User enters price_per_hour = 250 for 1h diagnosis
  → total = 250 (what client sees, goes into PDF)
  → salary_base = 250 × 0.80 = 200 (what mechanic gets salaried on)
  → applied_margin_pct = 20 (frozen)

If admin later changes Andrei's margin to 40%, the row's salary_base does
NOT change — history is immutable. Only new rows use the new margin.
Solves the retroactive-recompute problem for closed payroll periods.

== salary_base freeze semantics ==

wo_works gains 2 columns:
  salary_base decimal(10,2) nullable
  applied_margin_pct decimal(5,2) nullable

Frozen at save time by WorkOrderWork::saving hook. Recomputes only if
total OR master_id changes (i.e., someone actively edits the price or
reassigns the mechanic — in those cases we WANT the salary_base to
follow). Legacy rows (before this feature) have null salary_base;
PayrollCalculator falls back to total for them.

== PayrollCalculator uses salary_base ==

Previously: sum(wo_works.total) × works_pct → gave the mechanic a cut
of the price INCLUDING margin.

Now: sum(salary_base ?? total) × works_pct → the cut is from the
labor rate excluding margin.

Impact: for a 250 lei diagnosis at 20% margin with 50% payroll cut, the
mechanic gets 200 × 50% = 100 lei (was 250 × 50% = 125 lei). The shop
keeps the 50 lei margin regardless of the payroll %.

== RBAC gate ==

New permission FINANCE_VIEW_INTERNAL_MARGIN. Assigned to owner + admin +
manager + accountant in seed matrix. Not granted to mechanic,
receptionist, or viewer — those roles never see the "Bază salariu"
disclosure line or the margin % fields.

== UI surfaces ==

UserResource — new "Salariu & marjă" section (visible only with
FINANCE_VIEW_INTERNAL_MARGIN):
  - Tarif orar (MDL)
  - Marjă internă (%) with helper text explaining the -X% semantics
  - Placeholder tells manager the exact formula

WorkOrderResource form — new override_margin_pct field in the "Plată &
total" section, gated by same permission. Helper text: "Doar pentru
cazuri speciale. Lasă gol pentru a folosi marja mecanicului."

WorksRelationManager (WO edit page) — Total column now shows a gray
subtitle line "Bază salariu: 200.00 MDL · marjă 20%" ONLY for users
with FINANCE_VIEW_INTERNAL_MARGIN. Everyone else sees just Total.

== Contract tests: NO leak ==

InternalMarginTest verifies with black-box grepping that:
- WorkOrderPdfService::generate output contains NONE of
  {salary_base, internal_margin, applied_margin_pct, marja intern,
  Bază salariu}
- /api/track/{token} JSON payload contains NONE of the same terms
- wo_parts table has no salary_base column (margin ONLY on labor)
- Changing mechanic.internal_margin_pct after work is saved does NOT
  rewrite the historical salary_base (frozen)
- WO override wins over mechanic margin (contract-priced clients)
- Fallback chain: WO → mechanic → company default → 0

== Suite ==
298 passed (828 assertions). Was 285. +13 InternalMarginTest.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/Filament/Tenant/Resources/UserResource.php

@@ -90,6 +90,25 @@ class UserResource extends Resource
                         ->columnSpanFull()
                         ->helperText('Roluri suplimentare peste rolul primar — drepturile se cumulează.'),
                 ]),
+            Schemas\Components\Section::make('Salariu & marjă')
+                ->description('Configurează procentele pentru calcul salariu. Marja internă (nu TVA) se scade din prețul de manoperă pentru a determina baza salariului.')
+                ->columns(2)
+                ->visible(fn () => auth()->user()?->canDo(\App\Auth\Permissions::FINANCE_VIEW_INTERNAL_MARGIN) ?? false)
+                ->schema([
+                    Forms\Components\TextInput::make('hourly_rate')
+                        ->label('Tarif orar (MDL)')
+                        ->numeric()
+                        ->step(0.01)
+                        ->placeholder('Ex: 100'),
+                    Forms\Components\TextInput::make('internal_margin_pct')
+                        ->label('Marjă internă (%)')
+                        ->numeric()
+                        ->step(0.01)
+                        ->minValue(0)
+                        ->maxValue(90)
+                        ->placeholder('Ex: 20 pentru +20%')
+                        ->helperText('Doar la manopere (proprii + subcontract). Baza salariu = preț client × (1 − marjă/100). Lasă gol pentru a folosi valoarea implicită a companiei.'),
+                ]),
             Schemas\Components\Section::make('Securitate')
                 ->columns(2)
                 ->schema([

app/Filament/Tenant/Resources/WorkOrderResource.php

@@ -143,6 +143,15 @@ class WorkOrderResource extends Resource
                         ->default('unpaid')
                         ->required(),
                     Forms\Components\TextInput::make('discount_pct')->label('Discount %')->numeric()->default(0),
+                    Forms\Components\TextInput::make('override_margin_pct')
+                        ->label('Marjă internă (%) — override')
+                        ->numeric()
+                        ->step(0.01)
+                        ->minValue(0)
+                        ->maxValue(90)
+                        ->placeholder('Ex: 25 pentru VIP / contract')
+                        ->helperText('Doar pentru cazuri speciale. Lasă gol pentru a folosi marja mecanicului.')
+                        ->visible(fn () => auth()->user()?->canDo(\App\Auth\Permissions::FINANCE_VIEW_INTERNAL_MARGIN) ?? false),
                     Forms\Components\TextInput::make('total')->label('Total')->numeric()->disabled()->dehydrated(false),
                     Forms\Components\Toggle::make('approved')->label('Aprobat de client'),
                     Forms\Components\DatePicker::make('closed_at')->label('Închis'),

app/Filament/Tenant/Resources/WorkOrderResource/RelationManagers/WorksRelationManager.php

@@ -61,7 +61,13 @@ class WorksRelationManager extends RelationManager
                 Tables\Columns\TextColumn::make('name')->label('Manoperă')->wrap(),
                 Tables\Columns\TextColumn::make('hours')->label('Ore')->numeric(decimalPlaces: 2)->alignRight(),
                 Tables\Columns\TextColumn::make('price_per_hour')->label('Preț/h')->money('MDL')->alignRight(),
-                Tables\Columns\TextColumn::make('total')->label('Total')->money('MDL')->alignRight(),
+                Tables\Columns\TextColumn::make('total')
+                    ->label('Total')
+                    ->money('MDL')
+                    ->alignRight()
+                    ->description(fn ($record) => (auth()->user()?->canDo(\App\Auth\Permissions::FINANCE_VIEW_INTERNAL_MARGIN) && $record->salary_base !== null)
+                        ? 'Bază salariu: ' . number_format((float) $record->salary_base, 2) . ' MDL · marjă ' . rtrim(rtrim(number_format((float) $record->applied_margin_pct, 2), '0'), '.') . '%'
+                        : null),
                 Tables\Columns\TextColumn::make('master.name')->label('Maistru')->placeholder('—'),
                 Tables\Columns\TextColumn::make('status')
                     ->formatStateUsing(fn ($s) => WorkOrderWork::STATUSES[$s] ?? $s)