Phase 1 server: TLS + token auth, session registry, EchoDriver, SSE with cursors

The whole pipe behind one Driver trait and a common event model:
spawn/list/delete sessions, message + question answering, append-only
JSONL transcripts whose sequence numbers are the phone's resume cursor
(surviving backend restarts), bearer-token middleware wrapping every
route including the fallback, wg0-only binding that fails closed, and
first-run token enrollment via a terminal QR.

Verified: cargo test (10), clippy clean, and curl end-to-end over pinned
TLS -- auth rejection, spawn, streamed SSE replay/resume, /question
round trip, restart continuing seq numbers, delete removing everything.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017xn8nHw1tw1R6PtiY1eEtw

server/Cargo.toml

@@ -0,0 +1,37 @@
+[package]
+name = "ai-server"
+version = "0.1.0"
+edition = "2024"
+
+[[bin]]
+name = "ai-server"
+path = "src/main.rs"
+
+[dependencies]
+axum = { version = "0.8", features = ["json"] }
+axum-server = { version = "0.8", features = ["tls-rustls"] }
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "net", "sync", "time"] }
+tokio-stream = "0.1"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+clap = { version = "4", features = ["derive"] }
+anyhow = "1"
+thiserror = "2"
+# Token auth: hash for storage, constant-time compare for verification,
+# CSPRNG-backed generation, base64url for the enrollment string.
+sha2 = "0.11"
+subtle = "2"
+rand = "0.10"
+base64 = "0.23"
+# Renders the enrollment QR straight to the terminal; no image output needed.
+qrcode = { version = "0.14", default-features = false }
+# The wg0-bound listener needs the interface's address; the stdlib has no
+# getifaddrs. This is the smallest crate that wraps just that.
+if-addrs = "0.15"
+
+[dev-dependencies]
+tempfile = "3"
+# ServiceExt::oneshot, to drive the auth middleware without a socket.
+tower = { version = "0.5", features = ["util"] }