Complete ORM gaps + server features + module depth push

ORM:
- SQL Constraints support (Model.AddSQLConstraint, applied in InitDatabase)
- Translatable field Read (ir_translation lookup for non-en_US)
- active_test filter in SearchCount + ReadGroup (consistency with Search)
- Environment.Ref() improved (format validation, parameterized query)

Server:
- /web/action/run endpoint (server action execution stub)
- /web/model/get_definitions (field metadata for multiple models)
- Binary field serving rewritten: reads from DB, falls back to SVG
  with record initial (fixes avatar/logo rendering)

Business modules deepened:
- Account: action_post validation (partner, lines), sequence numbering
  (JOURNAL/YYYY/NNNN), action_register_payment, remove_move_reconcile
- Sale: action_cancel, action_draft, action_view_invoice
- Purchase: button_draft
- Stock: action_cancel on picking
- CRM: action_set_won_rainbowman, convert_opportunity
- HR: hr.contract model (employee, wage, dates, state)
- Project: action_blocked, task stage seed data

Views:
- Cancel/Reset buttons in sale.form header
- Register Payment button in invoice.form (visible when posted+unpaid)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/server/server.go

@@ -100,6 +100,10 @@ func (s *Server) registerRoutes() {
 	// Action loading
 	s.mux.HandleFunc("/web/action/load", s.handleActionLoad)
 	s.mux.HandleFunc("/web/action/load_breadcrumbs", s.handleLoadBreadcrumbs)
+	s.mux.HandleFunc("/web/action/run", s.handleActionRun)
+
+	// Model definitions
+	s.mux.HandleFunc("/web/model/get_definitions", s.handleGetDefinitions)
 
 	// Database endpoints
 	s.mux.HandleFunc("/web/database/list", s.handleDBList)