fix(server): web UI listens on IPv6 — the mesh could never load it

The mesh is IPv6-only; the main web listener bound 0.0.0.0 only, so a
phone reaching a node over its fips0 ULA got RST on :80
(ERR_CONNECTION_ABORTED) — UI over mesh was structurally impossible.
Confirmed 2026-07-26 on framework-pt: v4:80 = 200, v6:80 = refused.
Mirror an IPv4-any main listener with a V6ONLY [::] socket on the same
port; V6ONLY so it coexists with the v4 listener regardless of
net.ipv6.bindv6only.

Also: fips.yaml generator carries the fast-reconnect profile (validated
live on framework-pt since 2026-07-24; snapshot tests updated).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/fips/config.rs

@@ -48,6 +48,30 @@ pub struct FipsConfig {
 pub struct NodeSection {
     pub identity: IdentitySection,
     pub discovery: DiscoverySection,
+    pub retry: RetrySection,
+    pub rate_limit: RateLimitSection,
+}
+
+/// Fast-reconnect profile (`node.retry.*`). Upstream defaults (5s base
+/// doubling to 300s) are tuned for stable always-on links; a node redialing
+/// a recycled anchor sat off-mesh for ~90s. Field names verified live on
+/// 2026-07-24: a daemon restarted with these keys in fips.yaml and peered.
+#[derive(Debug, Clone, PartialEq, Serialize)]
+pub struct RetrySection {
+    pub base_interval_secs: u64,
+    pub max_backoff_secs: u64,
+    pub max_retries: u32,
+}
+
+/// Session-handshake resend pacing (`node.rate_limit.*`). Stock 1s x2.0
+/// gaps out to 8-16s between resends exactly when a route has just
+/// appeared; 400ms x1.5 keeps continuous coverage through the connect
+/// window (phone measured session-after-route: 225ms).
+#[derive(Debug, Clone, PartialEq, Serialize)]
+pub struct RateLimitSection {
+    pub handshake_resend_interval_ms: u64,
+    pub handshake_resend_backoff: f64,
+    pub handshake_max_resends: u32,
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize)]
@@ -60,6 +84,14 @@ pub struct IdentitySection {
 
 #[derive(Debug, Clone, PartialEq, Serialize)]
 pub struct DiscoverySection {
+    /// Lookup completion timeout. Lookups fired while the tree position is
+    /// still settling are doomed; failing them fast (5s, not 10s) lets the
+    /// 1s-backoff retry find the route the moment it exists.
+    pub timeout_secs: u64,
+    pub backoff_base_secs: u64,
+    pub backoff_max_secs: u64,
+    pub retry_interval_secs: u64,
+    pub max_attempts: u8,
     pub lan: LanDiscoverySection,
 }
 
@@ -123,8 +155,23 @@ impl Default for FipsConfig {
             node: NodeSection {
                 identity: IdentitySection { persistent: true },
                 discovery: DiscoverySection {
+                    timeout_secs: 5,
+                    backoff_base_secs: 1,
+                    backoff_max_secs: 30,
+                    retry_interval_secs: 2,
+                    max_attempts: 3,
                     lan: LanDiscoverySection { enabled: true },
                 },
+                retry: RetrySection {
+                    base_interval_secs: 1,
+                    max_backoff_secs: 30,
+                    max_retries: 30,
+                },
+                rate_limit: RateLimitSection {
+                    handshake_resend_interval_ms: 400,
+                    handshake_resend_backoff: 1.5,
+                    handshake_max_resends: 10,
+                },
             },
             tun: TunSection {
                 enabled: true,
@@ -318,8 +365,21 @@ node:
   identity:
     persistent: true
   discovery:
+    timeout_secs: 5
+    backoff_base_secs: 1
+    backoff_max_secs: 30
+    retry_interval_secs: 2
+    max_attempts: 3
     lan:
       enabled: true
+  retry:
+    base_interval_secs: 1
+    max_backoff_secs: 30
+    max_retries: 30
+  rate_limit:
+    handshake_resend_interval_ms: 400
+    handshake_resend_backoff: 1.5
+    handshake_max_resends: 10
 tun:
   enabled: true
   name: fips0