LAMBDA file parsing and prefix rewriting

[jimmytacks]

Part of #1

Description

Parse .lambda files from disk, apply prefix-on-load, and inject into Name Manager.

Deliverables

• LambdaParser.cs — Parse .lambda file format: extract name from Name = LAMBDA(...) pattern, extract full formula body
• LibraryMetadata.cs — Deserialize _library.yaml (name, description, default_prefix)
• PrefixRewriter.cs — Text replacement Foo( → prefix.Foo( for all known names, skipping string literals ("..." with doubled-quote escaping)
• LambdaLoader.cs — Extend to accept a library folder path, parse all files, apply prefix, inject all

Dependencies

• YamlDotNet NuGet package for YAML parsing

Tests

• Unit tests for LambdaParser: various .lambda file formats, edge cases
• Unit tests for PrefixRewriter: basic replacement, string-literal exclusion, doubled quotes
• AddIn test: load test library from local folder, verify Name Manager entries with correct prefix

Depends on

• Tracer bullet: add-in skeleton + popup + Name Manager injection #2 (tracer bullet)