[M10/LNS-003] Implement lens composition engine

[flyingrobots]

LNS-003: Lens Composition Engine

Parent: #227 (M10 LENS)

What

Implement composeLenses() in src/lens.js and wire into renderView() in src/views.js via options.lenses parameter.

• composeLenses(lensNames) → returns a single function that chains lenses left-to-right
• renderView(graph, viewName, options) gains options.lenses (array of lens names)
• needsProperties propagates: if ANY lens in chain needs it, the view runs with properties

Why

Composition is what makes lenses powerful — view:lens1:lens2 applies transformations in sequence.

Acceptance Criteria

• composeLenses(['a', 'b']) applies a then b to ViewResult
• Unknown lens name → clear error with available lens list
• needsProperties propagation works correctly
• Wired into renderView() — passing lenses: ['incomplete'] works
• Empty lenses array = no-op (identity)
• Tests for composition order, error cases, needsProperties propagation

Dependencies

• LNS-002 (lens registry must exist)

[flyingrobots]

Implemented in M10 LENS milestone. Closing as done.