Move 26 run_worker command bodies into worker_commands.rs

[Sythos]

Refs #206.

Step 5 of the split of main.rs, first part (run_worker). The bodies of 26 arms (of 139) move into run_<command> functions in the new crates/cordiale-ui/src/worker_commands.rs, and each arm now just calls its helper, with .await exactly when the helper is async. run_worker goes from 1,237 to 996 lines and main.rs from 12,630 to 12,391. The frame is untouched: the loop, the match &mut session_events, the select!, every arm pattern and guard, so the order of events is preserved by construction. The issue stays open for the last part (main()).

Which arms moved: only those with a body of ten lines or more that contain no return, ?, label, break or continue, assign or borrow mutably no run_worker local other than state, need at most seven parameters and have only parameters and pattern bindings of declared types as free variables. The other 113 stay inline: 103 are shorter than ten lines, five use session_events (Connect, TotpVerify, ShareConsume, RecoverySignIn, PasskeySignIn), two use the radio locals (RadioTrack, Disconnect), two would need more than seven parameters (AdminServerEdit, AdminCredentialEdit) and one is the None => return frame arm. The helpers take state: &mut WorkerState and ui: &slint::Weak<AppWindow> like the existing handlers, plus the arm's bindings with the types of the WorkerCommand fields. They are named run_* (no existing item has those names).

Checked by script: every helper body equals the original arm body after one normalisation that moving the code requires (&mut state and &state become state, &ui becomes ui, since they are references already: otherwise &mut state would be a &mut &mut and &ui trips needless_borrow); every parameter is used and every call passes exactly the names the body needs; no return, ?, label, break or continue in a helper; the token stream of main.rs with the 26 bodies masked is identical to the original except the mod and use lines; the #[test] count is unchanged (305). The CI log should show the same test counts as main (390 for cordiale-ui). Not verified: nothing is compiled before CI. Disjoint field borrows through the &mut reference (the notify and admin refresh arms) and the futures' Send-ness are the points to watch.

Branch: enhancement-issue-206-worker