feat: add schema evolution type system integration and HTTP server effect

Schema Evolution:
- Preserve version info in type resolution (Type::Versioned)
- Track versioned type declarations in typechecker
- Detect version mismatches at compile time (@v1 vs @v2 errors)
- Support @v2+ (at least) and @latest version constraints
- Store migrations for future auto-migration support
- Fix let bindings to preserve declared type annotations

HTTP Server Effect:
- Add HttpServer effect with listen, accept, respond, respondWithHeaders, stop
- Implement blocking request handling via tiny_http
- Request record includes method, path, body, headers
- Add http_server.lux example with routing via pattern matching
- Add type-checking test for HttpServer effect

Tests: 222 passing (up from 217)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Cargo.lock

@@ -20,6 +20,12 @@ version = "1.0.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5f0e0fee31ef5ed1ba1316088939cea399010ed7731dba877ed44aeb407a75ea"
 
+[[package]]
+name = "ascii"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d92bec98840b8f03a5ff5413de5293bfcd8bf96467cf5452609f939ec6f5de16"
+
 [[package]]
 name = "autocfg"
 version = "1.5.0"
@@ -84,6 +90,12 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fd16c4719339c4530435d38e511904438d07cce7950afa3718a84ac36c10e89e"
 
+[[package]]
+name = "chunked_transfer"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e4de3bc4ea267985becf712dc6d9eed8b04c953b3fcfb339ebc87acd9804901"
+
 [[package]]
 name = "clipboard-win"
 version = "5.4.1"
@@ -808,6 +820,7 @@ dependencies = [
  "target-lexicon",
  "tempfile",
  "thiserror",
+ "tiny_http",
 ]
 
 [[package]]
@@ -1408,6 +1421,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tiny_http"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "389915df6413a2e74fb181895f933386023c71110878cd0825588928e64cdc82"
+dependencies = [
+ "ascii",
+ "chunked_transfer",
+ "httpdate",
+ "log",
+]
+
 [[package]]
 name = "tinystr"
 version = "0.8.2"