feat(openwrt): add archipelago-openwrt crate with TollGate provisioning

New `archipelago-openwrt` workspace crate provides SSH/UCI-based management
of OpenWrt routers, including automated TollGate installation and configuration
of a pay-as-you-go "archipelago" SSID backed by the local Cashu mint.

Exposes two RPC endpoints:
- `openwrt.scan` — discover OpenWrt routers on the LAN
- `openwrt.provision-tollgate` — install tollgate-module-basic-go, write UCI
  config (TIP-01/TIP-02), and create isolated WiFi SSID + firewall zone

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

core/openwrt/src/uci.rs

@@ -0,0 +1,59 @@
+use anyhow::Result;
+
+use crate::Router;
+
+/// Thin wrappers around `uci` CLI commands over SSH.
+impl Router {
+    /// `uci get <key>` — returns trimmed value.
+    pub fn uci_get(&self, key: &str) -> Result<String> {
+        let out = self.run_ok(&format!("uci get {}", key))?;
+        Ok(out.trim().to_string())
+    }
+
+    /// `uci set <key>=<value>`
+    pub fn uci_set(&self, key: &str, value: &str) -> Result<()> {
+        self.run_ok(&format!("uci set {}={}", key, shell_quote(value)))?;
+        Ok(())
+    }
+
+    /// `uci add <config> <type>` — returns the new section name.
+    pub fn uci_add(&self, config: &str, section_type: &str) -> Result<String> {
+        let out = self.run_ok(&format!("uci add {} {}", config, section_type))?;
+        Ok(out.trim().to_string())
+    }
+
+    /// `uci add_list <key>=<value>`
+    pub fn uci_add_list(&self, key: &str, value: &str) -> Result<()> {
+        self.run_ok(&format!("uci add_list {}={}", key, shell_quote(value)))?;
+        Ok(())
+    }
+
+    /// `uci delete <key>`
+    pub fn uci_delete(&self, key: &str) -> Result<()> {
+        self.run_ok(&format!("uci delete {}", key))?;
+        Ok(())
+    }
+
+    /// `uci commit [<config>]`
+    pub fn uci_commit(&self, config: Option<&str>) -> Result<()> {
+        match config {
+            Some(c) => self.run_ok(&format!("uci commit {}", c))?,
+            None => self.run_ok("uci commit")?,
+        };
+        Ok(())
+    }
+
+    /// Batch: apply a list of `(key, value)` pairs then commit the config.
+    pub fn uci_apply(&self, config: &str, pairs: &[(&str, &str)]) -> Result<()> {
+        for (key, value) in pairs {
+            self.uci_set(key, value)?;
+        }
+        self.uci_commit(Some(config))?;
+        Ok(())
+    }
+}
+
+/// Wrap a value in single quotes, escaping any embedded single quotes.
+fn shell_quote(s: &str) -> String {
+    format!("'{}'", s.replace('\'', r"'\''"))
+}