feat(db): enhance public key conflict handling (#4555)

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

core/database/README.md

@@ -1,5 +1,25 @@
 # `:core:database`
 
+This module provides the local Room database persistence layer for the application.
+
+## Key Components
+
+-   **`MeshtasticDatabase`**: The main Room database class.
+-   **DAOs (Data Access Objects)**:
+    -   `NodeInfoDao`: Manages storage and retrieval of node information (`NodeEntity`). Contains critical logic for handling Public Key Conflict (PKC) resolution and preventing identity wiping attacks.
+    -   `PacketDao`: Handles storage of mesh packets.
+    -   `ChatMessageDao`: Manages chat message history.
+-   **Entities**:
+    -   `NodeEntity`: Represents a node on the mesh.
+    -   `PacketEntity`: Represents a stored packet.
+
+## Security Considerations
+
+### Public Key Conflict (PKC) Handling
+The `NodeInfoDao` implements specific logic to protect against impersonation and "wipe" attacks:
+-   **Wipe Protection**: Receiving an `is_licensed=true` packet (which normally clears the public key for compliance) will **not** clear an existing valid public key if one is already known. This prevents attackers from sending fake licensed packets to wipe keys from the DB.
+-   **Conflict Detection**: If a new key arrives for an existing node ID that conflicts with a known valid key, the key is set to `ERROR_BYTE_STRING` to flag the potential impersonation.
+
 ## Module dependency graph
 
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