feat: Phase 4 – CSV-Import (Templates, Prüfansicht, Duplikat/Transfer-Erkennung, Undo)

Backend:
- Modelle + Migration 0005: import_templates, import_batches, categorization_rules;
  transactions um import_batch_id + import_hash erweitert.
- services/csv_import: Datei parsen (Trennzeichen, Dezimal-/Datumsformat, Kodierung,
  Header/Skip, Vorzeichen vs. Soll/Haben), Vorschau mit Duplikat-Erkennung (Hash),
  interner-Transfer-Erkennung via IBAN, lernender Auto-Kategorisierung; Buchen mit
  Batch und Undo.
- routers/imports: Templates (CRUD), Roh-Vorschau, Prüf-Vorschau, Buchen, Verlauf,
  Rückgängig. pytest: Parsing, Duplikate, Transfer, Buchen, Undo, Lernen.

Frontend:
- Import-Seite: Konto+Datei, Format/Spaltenzuordnung (mit Roh-Vorschau),
  editierbare Prüfansicht (Kategorie/Typ/Zielkonto, Duplikate markiert),
  Buchen, Import-Verlauf mit Undo; Vorlagen speichern; i18n DE/EN.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/schemas.py

@@ -6,9 +6,11 @@ from pydantic import BaseModel, ConfigDict, Field, field_validator
 
 from .models import (
     AccountType,
+    AmountMode,
     BudgetTreatment,
     CategoryKind,
     IdentifierKind,
+    ImportStatus,
     Role,
     TxnType,
 )
@@ -283,3 +285,63 @@ class PlannedIncomeOut(BaseModel):
     target_account_id: int | None
     planned_cents: int
     position: int
+
+
+# --- CSV-Import ------------------------------------------------------------
+
+
+class ImportTemplateCreate(BaseModel):
+    name: str = Field(min_length=1, max_length=120)
+    delimiter: str = ";"
+    decimal_sep: str = ","
+    date_format: str = "%d.%m.%Y"
+    encoding: str = "utf-8"
+    has_header: bool = True
+    skip_rows: int = 0
+    amount_mode: AmountMode = AmountMode.signed
+    column_map: dict[str, int | None] = Field(default_factory=dict)
+
+
+class ImportTemplateUpdate(BaseModel):
+    name: str | None = Field(default=None, min_length=1, max_length=120)
+    delimiter: str | None = None
+    decimal_sep: str | None = None
+    date_format: str | None = None
+    encoding: str | None = None
+    has_header: bool | None = None
+    skip_rows: int | None = None
+    amount_mode: AmountMode | None = None
+    column_map: dict[str, int | None] | None = None
+
+
+class ImportTemplateOut(BaseModel):
+    id: int
+    name: str
+    delimiter: str
+    decimal_sep: str
+    date_format: str
+    encoding: str
+    has_header: bool
+    skip_rows: int
+    amount_mode: AmountMode
+    column_map: dict[str, int | None]
+
+
+class ImportBatchOut(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    account_id: int
+    template_id: int | None
+    filename: str
+    row_count: int
+    imported_count: int
+    status: ImportStatus
+    created_at: datetime
+
+
+class ImportCommitIn(BaseModel):
+    account_id: int
+    template_id: int | None = None
+    filename: str = ""
+    rows: list[dict] = Field(default_factory=list)