feat(tray/notifications): multi-target monitoring engine + dispatch wizard
Adds a fyne-free notifications engine that derives one rule per (kind, param) from a multi-target SetupPlan (Wallets/DReps/Pools/ MonitorEverything) and emits Requests through a tumbling-window rate limiter; connection alerts bypass it (not wired to notification system except tests). The wizard gains three editable target sections with cross-template validation hints, overwrites notify_prefs on Apply, and no longer blocks finishing on the macOS test notification. Removes tray/adder_config.go (dead code — only its own tests called it; the live SetupPlan→YAML path is setup/codec.go::ToEngineConfig). Implements #685 Signed-off-by: Ales Verbic <[email protected]>