make dist -> make xpi , better installation process

Makefile

@@ -24,20 +24,28 @@
 # Usage:
 #   make            # typecheck and bundle into build/
 #   make test       # run the unit tests
-#   make dist       # build, then zip build/ into logsdu-<version>.zip
-#   make clean      # remove build/ and the zip
+#   make xpi        # build, then package build/ as logsdu-<version>.xpi
+#   make clean      # remove build/ and the package
 #
 # Dependencies are installed with pnpm, never npm:
 #   corepack pnpm install
 #
-# Load build/ in Firefox: about:debugging -> This Firefox ->
-# Load Temporary Add-on -> pick build/manifest.json
+# Permanent install (Firefox ESR, Developer Edition or Nightly):
+#   set xpinstall.signatures.required=false in about:config, then
+#   about:addons -> gear -> Install Add-on From File -> pick the .xpi
+#
+# Release Firefox refuses unsigned add-ons whatever that pref says. There the
+# same .xpi has to go through addons.mozilla.org as an unlisted add-on first,
+# which signs it automatically without publishing or reviewing it.
+#
+# Throwaway install for development: about:debugging -> This Firefox ->
+# Load Temporary Add-on -> pick build/manifest.json (dropped on restart).
 
 EXT_ID := logsdu
 VERSION := $(shell node -p "require('./package.json').version")
-DIST := $(EXT_ID)-$(VERSION).zip
+XPI := $(EXT_ID)-$(VERSION).xpi
 
-.PHONY: all build test dist clean check-deps
+.PHONY: all build test xpi clean check-deps
 
 all: build
 
@@ -53,16 +61,19 @@ build: check-deps
 	node_modules/.bin/tsc -noEmit -skipLibCheck
 	node esbuild.config.mjs production
 
-# A plain zip of build/ is exactly what AMO wants for signing.
-dist: build
-	rm -f $(DIST)
-	cd build && zip -qr ../$(DIST) .
-	@echo "Package: $(DIST)"
-	@echo "Upload it to addons.mozilla.org as an unlisted add-on to get a signed .xpi."
+# An .xpi is just a zip of the extension directory, with the manifest at the
+# top level rather than inside a wrapper folder. The same file installs
+# directly on ESR and uploads to AMO for signing.
+xpi: build
+	rm -f $(XPI)
+	cd build && zip -qr ../$(XPI) .
+	@echo "Package: $(XPI)"
+	@echo "Install: about:addons -> gear -> Install Add-on From File"
+	@echo "Needs xpinstall.signatures.required=false on ESR/Developer/Nightly."
 
 clean:
 	rm -rf build
-	rm -f $(EXT_ID)-*.zip
+	rm -f $(EXT_ID)-*.xpi $(EXT_ID)-*.zip
 
 # Fail with a useful message rather than a confusing "tsc: not found".
 check-deps: