Replaced data annotation with Fluent API configuration for BodyQueryResult.RawBody column mapping in RecDbContext, centralizing entity configuration and removing the [Column("REQUEST_BODY")] attribute from the entity class.
Added `HeaderQueryResult` and `BodyQueryResult` classes to represent
query results for headers and bodies, respectively. These classes
map their properties to database columns (`REQUEST_HEADER` and
`REQUEST_BODY`) using the `[Column]` attribute. Both properties
are nullable and immutable.
Updated `RecDbContext` to configure these entities as keyless
using the `HasNoKey()` method in the `OnModelCreating` method,
indicating they are used for read-only queries.
