feat: HTTP registry, app/bench harnesses, and DWARF #line maps

Ship QUALITY_PLAN sessions 31–33: fetchable package index URLs, showcase
app and micro/nexus benchmarks, and debugger-friendly C codegen.

- Registry: BUX_REGISTRY accepts http(s) URLs (curl/wget → ~/.bux/cache)
- E.2: make test-apps smoke for nexus/boko/simpledb/jwt-pitbul
- E.5: benches/micro + C/Nim/Zig twins; make bench-nexus (wrk)
- E.4: HIR locs → #line .bux; default -O0 -g; --release -O2; make test-dwarf

tools/smoke_registry.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 # Smoke: registry search + add + install + build with greet package (E.1)
+# Also verifies HTTP-fetchable registry index (E.1b).
 set -euo pipefail
 ROOT="$(cd "$(dirname "$0")/.." && pwd)"
 BUXC="$ROOT/buxc"
@@ -10,9 +11,17 @@ if [[ ! -x "$BUXC" ]]; then
 fi
 
 TMP=$(mktemp -d)
-trap 'rm -rf "$TMP"' EXIT
+HTTP_PID=""
+cleanup() {
+  if [[ -n "$HTTP_PID" ]]; then
+    kill "$HTTP_PID" 2>/dev/null || true
+    wait "$HTTP_PID" 2>/dev/null || true
+  fi
+  rm -rf "$TMP"
+}
+trap cleanup EXIT
 
-echo "=== bux search greet ==="
+echo "=== bux search greet (local file) ==="
 "$BUXC" search greet | tee "$TMP/search.out"
 grep -q greet "$TMP/search.out"
 
@@ -61,4 +70,40 @@ echo "=== bux run ==="
 "$BUXC" run . | tee "$TMP/run.out"
 grep -q "Hello, Bux!" "$TMP/run.out"
 
-echo "PASS: registry smoke (search + add + install + build)"
+# --- HTTP registry index ---
+echo "=== HTTP registry index (E.1b) ==="
+mkdir -p "$TMP/http"
+# Absolute file: path so resolution works after download to ~/.bux/cache
+cat > "$TMP/http/registry.toml" <<EOF
+[[package]]
+name = "greet"
+version = "0.1.1"
+source = "file:$ROOT/registry/packages/greet"
+description = "HTTP-served greet package"
+EOF
+
+# Free port via python
+PORT=$(python3 -c 'import socket; s=socket.socket(); s.bind(("127.0.0.1",0)); print(s.getsockname()[1]); s.close()')
+(
+  cd "$TMP/http"
+  python3 -m http.server "$PORT" --bind 127.0.0.1 >/dev/null 2>&1
+) &
+HTTP_PID=$!
+# Wait until server responds
+for _ in 1 2 3 4 5 6 7 8 9 10; do
+  if curl -fsS "http://127.0.0.1:${PORT}/registry.toml" >/dev/null 2>&1; then
+    break
+  fi
+  sleep 0.1
+done
+
+export BUX_REGISTRY="http://127.0.0.1:${PORT}/registry.toml"
+export BUX_REGISTRY_REFRESH=1
+"$BUXC" search greet | tee "$TMP/http_search.out"
+grep -q greet "$TMP/http_search.out"
+grep -q "http://127.0.0.1" "$TMP/http_search.out" || grep -q "cached" "$TMP/http_search.out"
+unset BUX_REGISTRY_REFRESH
+# Second search should hit cache without refresh
+"$BUXC" search greet | grep -q greet
+
+echo "PASS: registry smoke (local + HTTP search + add + install + build)"