Landlords configure a contract via checkboxes/selects (WLAN included,
furnished, utility billing model, notice period, deposit, rent
adjustment clause) and generate a PDF (pdfkit) that's automatically
attached to the contract's document list. Tenants sign their own
contract in-app by drawing a signature on a canvas; signing embeds the
signature image into a freshly generated final PDF and marks the
contract as signed with a timestamp.
New: Contract.wifiIncluded/furnished/utilityBillingModel (+ new
UtilityBillingModel enum), Contract.tenantSignatureUrl/signedAt.
New endpoints: POST /contracts/:id/generate-document (landlord/admin),
POST /contracts/:id/sign (tenant on own contract, or landlord/admin).
Explicitly a documentation template generated from app data, not a
legally reviewed contract — noted in the PDF itself.
Replaces the unused, never-wired-up single contractPdfUrl field with
contractDocumentUrls (String[]) so landlords can attach several files
per contract (signed lease, addenda, ...) instead of just one. New
endpoints: GET /contracts/documents (tenant sees own contract only,
landlord sees all — same visibility rule as the rest of the app),
POST/DELETE /contracts/:id/documents (landlord/admin only). Frontend
reuses the existing FileReader-to-data-URL upload pattern already used
for inventory photos, so files are stored inline like everywhere else
in this app rather than introducing a new storage mechanism.
