Add fipstop TUI monitoring tool with smoothed metrics and quality ind…

[jmcorgan]

…ices

fipstop: ratatui-based TUI for real-time monitoring of a running FIPS daemon.

Tabs and navigation:

• 8 navigable tabs: Node, Peers, Transports, Sessions, Tree, Filters, Performance, Routing
• Tab/BackTab navigation with group separators in tab bar
• Table views with selectable rows, detail drill-down panels, and scrollbars

Node tab:

• Runtime info: pid, exe path, uptime, control socket path, TUN adapter name
• Identity: npub, node_addr, ipv6 address
• State summary with peer/session/link/transport/connection counts
• TUN IPv6 traffic and forwarded transit traffic counters

Peers tab:

• Table with Name, Address, Conn, Depth, SRTT, Loss, LQI, Pkts Tx/Rx
• Detail panel: identity, connection info, transport cross-reference, tree/bloom state, link stats, MMP metrics with LQI

Sessions tab:

• Table with Name, Remote Addr, State, Role, SRTT, Loss, SQI, Path MTU, Last Activity
• Detail panel: identity, session info, traffic stats, MMP metrics with SQI

Transports tab:

• Hierarchical tree view: expandable transport parents with nested links (▼/▶ indicators, ├─/└─ tree chars, Space/Arrow to expand/collapse)
• Transport detail: type-specific stats (UDP/TCP/Ethernet)
• Link detail: peer cross-reference with MMP metrics and LQI

Performance tab:

• Link-layer MMP: SRTT, loss, ETX, LQI, goodput per peer
• Session-layer MMP: SRTT, loss, ETX, SQI, path MTU per session
• Trend indicators (rising/falling/stable) with context-aware coloring

Routing tab:

• Routing state: cache sizes, pending lookups, recent requests
• Coordinate cache: entries, fill ratio, TTL, expiry, avg age
• Statistics: forwarding, discovery request/response, error signal counters

Tree tab:

• Spanning tree position with 16 announce stats (inbound/outbound/cumulative)

Filters tab:

• Bloom filter announce stats, per-peer fill ratio and estimated node count

MMP metrics enhancements:

• Add etx_trend DualEwma for smoothed ETX tracking
• Add smoothed_loss() and smoothed_etx() accessors (long-term EWMA)
• LQI (Link Quality Index) = smoothed_etx * (1 + srtt_ms / 100)
• SQI (Session Quality Index) = same formula for session layer
• All loss/ETX displays prefer smoothed values with raw fallback

Control socket:

• Add smoothed_loss, smoothed_etx, lqi/sqi to show_peers, show_sessions, and show_mmp JSON responses
• Rename fips_address to ipv6_addr in show_status and show_peers
• Add tun_name and control_socket to show_status
• FHS-compliant 3-tier default path: $XDG_RUNTIME_DIR, /run/fips, /tmp

Node extensions:

• Add started_at/uptime() to Node
• Add tun_name() accessor

Docker sidecar updates:

• TCP transport support via FIPS_PEER_TRANSPORT env var
• Build scripts include fipstop binary