Class RotorNavigationService

Manages rotor-based navigation for the active trace via alt+shift+up and alt+shift+down

Purpose:

• Provide modal navigation over a trace by rotating through three modes.

Navigation modes:

• DATA_MODE: Default data browsing. Focus remains in the trace scope; no compare behavior.
• LOWER_VALUE_MODE: Navigate to the next/previous data point with a lower y-value relative to the current point (supports left/right and, when available, up/down semantics).
• HIGHER_VALUE_MODE: Navigate to the next/previous data point with a higher y-value relative to the current point (supports left/right and, when available, up/down semantics).

Responsibilities:

• Track the current rotor mode and expose helpers to cycle forward/backward across modes.
• Coordinate scope focus: entering a compare mode (LOWER/HIGHER) may switch focus to the rotor scope; returning to DATA_MODE restores focus to the trace scope.
• Delegate directional movement to the active AbstractTrace implementation using rotor-aware APIs, with a fallback to compare-based traversal when rotor methods are unavailable.

Mode management:

• getMode(): Returns the symbolic mode string for the current index.
• setMode(): Applies mode side-effects (e.g., restore trace scope in DATA_MODE).
• getCompareType(): Maps the current mode to 'lower' or 'higher' for compare operations (DATA_MODE falls back to 'lower').

Dependencies:

• Context: Provides the active trace and current scope.
• DisplayService: Toggles UI focus between scopes (trace vs. rotor).
• TextService: Reserved for user-facing feedback/messages and parity with other services.

Notes:

• UI-agnostic: this service contains no rendering logic and does not depend on the UI.
• Returns user-facing messages from movement methods when a move is not possible; callers may surface these through the ViewModel/UI.