feat(packaging): core distribution packages (deb + rpm + tar.gz) via nfpm

Previously only the Electron GUI had installers; server admins had to build the
core by hand (`make build` -> bare binary). This adds a first-class server
distribution:

- `make core-dist` -> packaging/core-dist.sh -> cmd/build/dist/
    llmsproxy_<ver>_amd64.deb        (systemd unit + adapters + example config)
    llmsproxy-<ver>.x86_64.rpm
    llmsproxy-<ver>-linux-amd64.tar.gz
- nfpm config (packaging/nfpm.yaml): binary to /usr/bin, systemd unit with the
  measured memory tuning (GOGC=50, MALLOC_ARENA_MAX=2) baked in, Lua adapters to
  /usr/share/llmsproxy/adapters, repo's config.yaml as the example.
- postinst seeds /etc/llmsproxy/config.yaml on first install and keeps existing
  runtime state across reinstalls; prerm stops the service on removal.

Gotchas handled: nfpm v2 here does not render `{{ .Env.VERSION }}`, so the script
stamps the version into a throwaway config copy; and under `set -o pipefail` the
idiom `strings | grep -q` is broken (grep -q closes the pipe and strings dies on
SIGPIPE -> spurious 141), so the symbol sanity-gate stages strings in a temp file.

README (zh/en) updated: memory figures replaced with production-measured
32-35 MB settled (was 37-42), and the packaging docs now describe core-dist and
the dockerized Windows build.

Makefile

@@ -23,6 +23,14 @@ build:
 	CGO_ENABLED=1 go build -tags luajit -trimpath -o $(BUILD_DIR)/$(BINARY) ./cmd/llmsproxy
 	@echo "Built: $(BUILD_DIR)/$(BINARY) ($(VERSION))"
 
+# ---- core distribution packages (deb + rpm + tar.gz) -----
+# Server admins install these with dpkg/rpm; unlike the GUI they are the bare
+# gateway binary + systemd unit (with memory tuning) + Lua adapters.
+core-dist:
+	./packaging/core-dist.sh $(VERSION)
+
+.PHONY: core-dist
+
 # ---- GUI (Electron) ----
 gui:
 	@cd $(GUI_DIR) && npm start
@@ -36,6 +44,7 @@ gui-dev:
 # binary does not link against host-only libs and crash on user machines.
 gui-dist:
 	@cd $(GUI_DIR) && $(CLEAN_PACK_ENV) npm run dist:linux
+	./packaging/verify-dist.sh
 
 # deb only (for local sharing), rpm needs rpmbuild
 gui-deb:
@@ -48,6 +57,7 @@ gui-win:
 # windows nsis installer: full cross-build in docker (self-sufficient, no host mingw)
 gui-win-docker:
 	@cd $(GUI_DIR) && $(CLEAN_PACK_ENV) ./scripts/dist-win-docker.sh
+	./packaging/verify-dist.sh
 
 gui-dist-dir:
 	@cd $(GUI_DIR) && $(CLEAN_PACK_ENV) npm run dist:dir
@@ -61,6 +71,7 @@ clean:
 help:
 	@echo "Targets:"
 	@echo "  make build      build core binary (luajit)"
+	@echo "  make core-dist  build core packages: deb + rpm + tar.gz (needs nfpm)"
 	@echo "  make gui        run desktop GUI (dev)"
 	@echo "  make gui-dev    run GUI with devtools"
 	@echo "  make gui-dist   build deb + rpm + AppImage (linux)"