feat: update landlord profile management to link with OIDC subjects

docs/adr/0010-link-landlord-profiles-to-oidc-subjects.md

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+# Link Landlord Profiles to OIDC Subjects
+
+**Status**: accepted
+
+## Context
+
+ADR-0001 keeps the property portfolio shared and initially creates a default landlord. Connected accounts now need their own personal landlord profile for generated leases and rent receipts.
+
+## Decision
+
+- A landlord profile is identified by the stable OIDC subject (`sub`) of its connected account.
+- The e-mail address is a required, unique and mutable contact field; it is not the technical identifier.
+- A connected account can read and update only its own landlord profile.
+- This delivery does not partition apartments, leases or rent payments by account; the shared portfolio from ADR-0001 remains unchanged.
+
+## Consequences
+
+The application must obtain the OIDC subject from the authenticated principal for every profile operation. A future move to separate portfolios remains a distinct migration and decision.