Make pagination docs friendlier to subclasses

Safir really struggles to resolve references in inherited docstrings
when they reference the context of the upstream module from which
they are inherited. Use absolute references in the docstrings for the
pagination code in the hope that this will be friendlier to downstream
projects using Sphinx.

safir/src/safir/database/_pagination.py

@@ -113,10 +113,10 @@ def from_entry(cls, entry: E, *, reverse: bool = False) -> Self:
 
         Builds a cursor to get the entries after the provided entry, or before
         the provided entry if ``reverse`` is set to `True`. When the cursor is
-        later applied with `apply_cursor`, forward cursors (the default) must
-        include the entry the cursor was based on. Reverse cursors must
-        exclude the given entry and return data starting with the entry
-        immediately previous.
+        later applied with `~safir.database.PaginationCursor.apply_cursor`,
+        forward cursors (the default) must include the entry the cursor was
+        based on. Reverse cursors must exclude the given entry and return data
+        starting with the entry immediately previous.
 
         Parameters
         ----------
@@ -127,7 +127,7 @@ def from_entry(cls, entry: E, *, reverse: bool = False) -> Self:
 
         Returns
         -------
-        PaginationCursor
+        safir.database.PaginationCursor
             Requested cursor.
         """
 
@@ -148,7 +148,7 @@ def from_str(cls, cursor: str) -> Self:
 
         Raises
         ------
-        InvalidCursorError
+        safir.database.InvalidCursorError
             Raised if the cursor is invalid.
         """