android: strip Go binary via -s -w in gomobile bind

The Android gomobile target was the only ldflags site in the Makefile
not passing -s -w. Every other Go build (line 195, 219, 321, 329) does.
Confirmed via go-size-analyzer that libgojni.so retains gopclntab /
moduledata in the current build despite the NDK linker stripping the
ELF symbol table. Adding -s -w to ANDROID_GOMOBILE_LDFLAGS should
recover ~10-30 MB on the 82 MB libgojni.so for arm64.

This is on top of the arm32 drop + ML Kit unbundle + jniLibs excludes
in the prior commits on this branch — combined we expect APK size
to land somewhere in the ~40-45 MB range from the 93 MB baseline.

Follow-ups still on the table (separate PRs):

  1. with_tailscale sing-box tag: pulls in sagernet/tailscale (10K
     string occurrences in the binary, single largest contributor).
     Client never invokes the tailscale outbound — Headscale plumbing
     is server-side bandit fleet only.
  2. lantern-water/downloader's magnet:?  URL branch pulls in
     anacrolix/torrent + btree + dht. Split behind a build tag in
     lantern-water (off by default); we only use HTTPS retrieval.
  3. with_clash_api / with_acme / with_dhcp: review each — likely
     server-side or unused on the client.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: myleshorton

Makefile

@@ -120,7 +120,7 @@ ANDROID_SDK_ROOT             := $(or $(ANDROID_SDK_ROOT),$(ANDROID_HOME))
 SDKMANAGER                   := $(ANDROID_SDK_ROOT)/cmdline-tools/latest/bin/sdkmanager
 ANDROID_PAGE_SIZE ?= 16384
 # Android 15+ Play requirement: arm64 native libs must be linked for 16 KB page-size compatibility.
-ANDROID_GOMOBILE_LDFLAGS ?= -checklinkname=0 -extldflags=-Wl,-z,max-page-size=$(ANDROID_PAGE_SIZE),-z,common-page-size=$(ANDROID_PAGE_SIZE)
+ANDROID_GOMOBILE_LDFLAGS ?= -s -w -checklinkname=0 -extldflags=-Wl,-z,max-page-size=$(ANDROID_PAGE_SIZE),-z,common-page-size=$(ANDROID_PAGE_SIZE)
 
 IOS_INSTALLER := $(INSTALLER_NAME)$(if $(filter-out production,$(BUILD_TYPE)),-$(BUILD_TYPE)).ipa
 IOS_DIR := ios/