Rewrite jwt-pitbul and boko-framework with modern Bux constructs

- jwt-pitbul: algebraic enums, Array<String>, methods on JwtAlg,
  string interpolation, structured Result/Option error handling.
- boko-framework: StringMap<String> for headers/query/path params,
  Request/Response methods, StringBuilder, for loops, algebraic enums.
- Update READMEs and bump versions to 0.2.0.

apps/boko-framework/bux.toml

@@ -1,6 +1,6 @@
 [Package]
 Name    = "boko-framework"
-Version = "0.1.0"
+Version = "0.2.0"
 Type    = "bin"
 Description = "Boko — async web framework for Bux, inspired by FastAPI"