a dot should be a word-boundary when using <alt> + <left> or <alt> + <right>

I sometimes try to select the table name without the schema (or vice-versa) using ` + + `, but I always end up selecting the table name and the schema. Double clicking correctly recognises the dot as a word boundary and selects only the schema or the table name.

Reproduce the keyboard-selection behavior described with Alt+Shift+Left or Right, comparing it with double-click selection around a dot. Trace the desktop text-selection entry point that handles word boundaries, then verify that schema and table names can be selected independently without changing other word navigation behavior.

Written by the indexing model from the issue text.