Add bridge name column to --list-networks

list_networks_command() now includes each network's bridge name
(recomputed via bridge_name(), not stored -- it's already a pure
deterministic function of the network name), tab-aligned the same way
as the existing name/kind/subnet columns, positioned before the
trailing unaligned IPv6 column. Useful for correlating a network entry
with its live host-side state (`ip link show <bridge>`,
`iptables -t nat -L`) without recomputing the hash by hand.

Verified as root via the doas rule against a fresh extern and intern
network.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gv3s5jckJKzh6JkMoi2Akz

CLAUDE.md

@@ -177,8 +177,11 @@ Source layout (all under `src/`):
   the entry appended to `config.networks` and persisted; a network that
   fails to provision isn't saved. `list_networks_command()` reuses the same
   independently-per-column tab-alignment scheme as `list_processes_command()`
-  (name/kind/subnet each aligned, then the IPv6 subnet — or `"(no ipv6)"` —
-  appended unaligned as the trailing column, nothing follows it).
+  (name/kind/subnet/bridge each aligned — the bridge name recomputed via
+  `bridge_name(network.name)` — `network_bridge.h` — rather than stored, since
+  it's already a pure deterministic function of the name — then the IPv6
+  subnet — or `"(no ipv6)"` — appended unaligned as the trailing column,
+  nothing follows it).
   `delete_network_command()` currently only removes the config entry, the
   same as `delete_volume_command()`'s default (non-`-full`) behavior — it
   does not tear down the network's live bridge/namespace/iptables state (no