fix(13-02): retire the Python model-proxy sidecar and the OpenRouter open relay

Closes the live production exposure this plan targets: /aiui/api/claude/
and /aiui/api/ollama/ proxied straight through with "no session gate
needed", and /aiui/api/openrouter/ was a plain unauthenticated relay to a
paid third-party API the node holds no key for (T-13-08/T-13-09/T-13-10).

image-recipe/configs/nginx-archipelago.conf (BOTH server blocks, ~line 49
and ~line 961 — a fix applied to only one leaves the exposure live on
whichever block serves the request, T-13-15):
- /aiui/api/claude/ and /aiui/api/ollama/ proxy_pass re-pointed from
  127.0.0.1:3142 / 127.0.0.1:11434 to the Rust daemon at 127.0.0.1:5678
  (no trailing path component, so the daemon's own prefix match sees the
  full request URI)
- Forward the session Cookie header to the daemon so it can re-derive auth
- location /aiui/api/openrouter/ deleted outright in both blocks
- Old comment "API key managed by proxy, no session gate needed" (the
  reasoning error that produced the exposure) replaced with rationale

scripts/deploy-to-target.sh: deleted the embedded claude-api-proxy.py
heredoc, its systemd unit creation/enable/restart, the ANTHROPIC_API_KEY
extraction, and the 3141->3142 sed fixups. Added an unconditional step that
stops/disables/removes any pre-existing claude-api-proxy unit and deletes
/opt/archipelago/claude-api-proxy.py and
<data_dir>/secrets/claude-api-proxy.env on every deploy — so
already-provisioned nodes actually lose the old unauthenticated listener,
not just newly-deployed ones.

scripts/setup-aiui-server.sh: dropped the hard ANTHROPIC_API_KEY
requirement and the patch-nginx-claude.py step; the script's remaining job
is the AIUI dist rsync. (Also drops the FileBrowser-fix step that lived
here — that logic already exists, and is kept, in deploy-to-target.sh; this
script narrows to exactly what its rewritten header now says it does.)

core/archipelago/src/api/rpc/system/handlers.rs: `claude_api_key` setting
branch no longer writes a second key copy to secrets/claude-api-proxy.env
or restarts claude-api-proxy. secrets/claude-api-key (0600) remains the
single ledger, with a comment naming it as such.

`cargo build --package archipelago` succeeds. Verified via grep against
every acceptance criterion in 13-02-PLAN.md's Task 2 (openrouter count 0,
3142 gone from nginx, both location blocks present, PORT=3142 gone,
claude-api-proxy gone from handlers.rs, secrets/claude-api-key present).
Task 3 (real-node curl/systemd verification, S-15) is NOT done in this
commit — see 13-02-SUMMARY.md.

Continues WIP checkpoint 13b576da (reset --soft, recommitted atomically
per task per plan protocol).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/archipelago/src/api/rpc/system/handlers.rs

@@ -1049,22 +1049,12 @@ impl RpcHandler {
                     info!("Claude API key saved");
                 }
 
-                // Update the claude-api-proxy environment and restart
-                let env_line = format!("ANTHROPIC_API_KEY={}", value);
-                let env_file = self.config.data_dir.join("secrets/claude-api-proxy.env");
-                tokio::fs::write(&env_file, &env_line).await.ok();
-                #[cfg(unix)]
-                {
-                    use std::os::unix::fs::PermissionsExt;
-                    std::fs::set_permissions(&env_file, std::fs::Permissions::from_mode(0o600))
-                        .ok();
-                }
-
-                // Restart the proxy to pick up the new key
-                let _ = tokio::process::Command::new("sudo")
-                    .args(["systemctl", "restart", "claude-api-proxy"])
-                    .output()
-                    .await;
+                // `secrets/claude-api-key` (above) is deliberately the ONLY
+                // Claude key ledger on this node (13-02-PLAN.md). A second
+                // copy used to be written alongside it for a standalone,
+                // unauthenticated sidecar process on port 3142 — that
+                // sidecar and its key copy are retired; the session-gated
+                // Rust daemon reads this one file directly.
 
                 Ok(serde_json::json!({ "saved": true }))
             }