Phase 7: ns declaration + multi-file compilation

T7.1: Namespace declaration parsing
  (ns my.app (:require [lib :as l])) with :require/:as support
  Hyphen-to-underscore filename convention (math-utils -> math_utils.clj)

T7.2: Multi-file compilation
  Resolves requires, recursively loads dependencies
  Inlines all defs into single Nim file
  Namespace alias resolution (mu/square -> square)

86 tests pass, all examples work.

docs/ROADMAP.md

@@ -61,8 +61,8 @@
 - [x] `type`, `instance?`, `satisfies?`
 
 ## Phase 7: Project Compilation
-- [ ] Compile entire projects (not just single files)
-- [ ] Namespace system (`ns`, `require`, `use`)
+- [x] Compile entire projects (not just single files)
+- [x] Namespace system (`ns`, `(:require [lib :as alias])`)
 - [ ] Module caching for faster REPL startup
 - [ ] Dependency resolution