Implement the lazy Analysis Manager DAG #7

The AnalysisManager is the core of the engine and belongs to Phase 1 infrastructure.

• Registry of analyses and their declarative dependencies (dependency DAG, not a rigid chain)
• Uniform API: ctx.get(SymbolAnalysis), ctx.get(CFGAnalysis, function), ctx.get(TaintAnalysis, function)
• Lazy evaluation at module and function granularity; ctx.get(CFGAnalysis, foo) must not build every CFG in the project
• In-memory cache keyed by analysis type and module/function target; analyses declare a version. Persistent cache keyed by IR fingerprint and plugin/API version is deferred to Phase 10
• Two pass families: AnalysisPass (read-only) and TransformationPass; transformations declare what they preserve and invalidate
• Shared results are computed once regardless of how many plugins request them
• Expose the Phase 2 semantic results (ScopeAnalysis, ImportAnalysis, SymbolAnalysis) as the first registered analyses

Reference: docs/architecture.md §8 Analysis Manager, §9 Analysis DAG, §10 Lazy Evaluation, §11 Cache, §12 Invalidation.

Delivery: #8