Task: Add a language selector

A person changes the language of the web client from the shell and the choice is kept.

• A selector lists English, Portuguese and French, and a choice changes every screen at once.
• The choice is stored in the browser, as the stored value is read today.

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)

Every number this task claims about a tree, with the command that produced it and the commit it was measured at. A number without both is not a measurement, because a clean-up record describes a tree and trunk moves under a branch: a consumer count, a gate's component count and a suite's size all change with no code changing, and the reader of a bare number cannot tell which tree it came from. Where the raw output matters, put it in an evidence/ file beside the task and name that file in the Command column.

Manual QA scenarios (scaffolded via compass add test_scenario) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.

The account menu has a Language choice that lists English, Portuguese and French, each in its own language. The choice changes every screen at once and is stored in the browser under the key the client already read.