Adds `TargetSelectionClient` (Godot, HTTP to NEO-23 targeting endpoints):
- Tab cycles ids in ascending order matching `PrototypeTargetRegistry`
(`prototype_target_alpha`, `prototype_target_beta`) and wraps.
- Esc clears by POSTing with `targetId` omitted.
- UI always paints from the server's authoritative `targetState`
(success and denials alike); `UICanvas/TargetLockLabel` shows
`lockedTargetId`, `validity`, `sequence`, and (on deny) `reasonCode`.
- Movement-triggered refresh: while a lock is held, subsequent
`authoritative_position_received` snaps fire a throttled GET
(~250 ms cooldown) so `validity` flips to `out_of_range` after
locomotion without duplicating server radius math on the client.
Registers `target_tab` (Tab) / `target_clear` (Esc) in `project.godot`;
documents bindings + manual QA in `client/README.md`.
Tests: `target_selection_client_test.gd` covers GET parse, tab ordering
from empty/alpha/wrap, POST body shape, denial preserves server state,
clear omits targetId, movement refresh fires only while locked, cooldown
collapses bursts to one GET, and `apply_as_snap=false` is ignored.
All 85 client GdUnit cases pass; gdlint and gdformat clean.
See `docs/plans/NEO-24-implementation-plan.md`.
VinPropane