feat(mihomo): keep unproxiable ranges out of TUN, fix the startup DNS race (#419)

* feat(mihomo): keep ranges that can never be proxied out of TUN

The list lives in policy.yaml as tun_exclude_address; sources.yaml may override
it. 198.18.0.0/15 stays in TUN: that is the fake-ip range itself.

* feat(mihomo): match Valve's content servers by ASN

The 20 hand-copied prefixes had drifted from what AS32590 announces. The rule
type needs GeoLite2-ASN.mmdb, so geox-url.asn points at the same mirror.

* feat(mihomo): render the gateway config from the same sources

The hand-kept copy had drifted: a manual sync carried the desktop's secret onto
the gateway and dropped external-ui-url. --redact yields a shareable template.

* fix(mihomo): open the link DNS takeover only once the core serves it

The core opens :1053 after parsing rules, and rule parsing is where missing
geodata gets fetched. Flipping at fork time made that fetch SERVFAIL, the config
fatal, and the unit unstartable.

* fix(justfile): keep local endpoints out of the agent proxy

With only HTTP_PROXY set, a request to this host's own llama-swap endpoint went
to mihomo. Node matches exact hosts only, so the literals carry it; the CIDRs
serve curl and Go.

* feat(justfile): seed mihomo geodata into the service state dir

So a cold start never needs the download that the DNS takeover made unstartable.

Justfile

@@ -276,12 +276,46 @@ k3s-test mode="switch":
 [group('agents')]
 dsh-web:
   #!/usr/bin/env nu
-  # dsh's web fetch refuses a DNS answer it does not call public, and a fake-ip
-  # resolver answers with 198.18.0.0/15. A proxied hop lets mihomo resolve the
-  # origin instead, which skips that check and leaves fake-ip acceleration
-  # intact. The policy reaches every Node fetch the harness makes, so mihomo
-  # becomes a dependency for LLM, web search and HTTP MCP traffic too.
-  with-env { HTTPS_PROXY: "http://127.0.0.1:7897", HTTP_PROXY: "http://127.0.0.1:7897" } { ^dsh web --no-open }
+  # no_proxy keeps local endpoints out of the proxy; the proxy is here for fake-ip.
+  # dsh's web fetch refuses a DNS answer it does not call public and fake-ip answers
+  # with 198.18.0.0/15, so a proxied hop makes mihomo resolve the origin instead.
+  # That makes mihomo a dependency of every Node fetch the harness makes, so it has
+  # to stop at the LAN: without no_proxy this host's own llama-swap endpoint goes
+  # through it too. Node reads only lowercase `no_proxy` and matches exact hosts,
+  # not CIDR; curl and Go do honor CIDR.
+  with-env {
+    HTTPS_PROXY: "http://127.0.0.1:7897"
+    HTTP_PROXY: "http://127.0.0.1:7897"
+    no_proxy: "localhost,127.0.0.1,::1,[::1],192.168.5.100,192.168.5.178,10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
+    NO_PROXY: "localhost,127.0.0.1,::1,[::1],192.168.5.100,192.168.5.178,10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
+  } { ^dsh web --no-open }
+
+# Seed mihomo's geodata into the service's state dir, so a cold start needs no DNS.
+[linux]
+[group('services')]
+mihomo-geo:
+  #!/usr/bin/env nu
+  # Copy geodata in by hand, so a cold start never has to fetch it. The core
+  # fetches it while parsing rules, before its own DNS is up and while the link
+  # DNS points at it -- that fetch can only fail.
+  let src = ($env.HOME | path join .config mihomo)
+  let dst = "/var/lib/private/mihomo"
+  sudo mkdir -p $dst
+  mut seeded = []
+  for f in [GeoSite.dat geoip.metadb ASN.mmdb] {
+    let p = ($src | path join $f)
+    if ($p | path exists) {
+      sudo cp $p $dst
+      $seeded = ($seeded | append ($dst | path join $f))
+    } else {
+      print $"(!) ($f) is not in ($src) -- fetch it first: mihomo -t -d ($src) -f ($src)/config.yaml"
+    }
+  }
+  if ($seeded | is-not-empty) {
+    sudo chmod 644 ...$seeded
+    let names = ($seeded | path basename | str join ', ')
+    print $"seeded ($names) -- restart mihomo to pick them up"
+  }
 
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