decommission Pi: update all docs for VM-only setup

The orchestrator Pi is retired (2026-05-31). All agents now run on the
cc-ci-orchestrator VM (NixOS, loops user, /srv/cc-ci). The VM is a
direct tailnet peer to cc-ci — no SOCKS proxy, no userspace tailscaled,
no ProxyCommand. Updated across all affected files:

AGENTS.md
  - Remove Pi from reboot description; migration complete (not "parked")
  - cc-ci access: direct ssh, not via proxy

kickoff.md
  - Prerequisites: direct tailnet peer, not proxy
  - Host deps: NixOS (not apt)
  - Fallback/Incus: b1 reachable directly, no --proxy curl flag

plan.md §1 + §1.5
  - §1 bootstrap: direct SSH, check tailscale status (not restart proxy)
  - §1.5 intro: "VM" not "sandbox host"; no proxy
  - Credentials table: remove TS_AUTH_KEY row; update cc-ci SSH row
  - Replace "Tailscale connection (proxy)" subsection with direct-peer description

plan-orchestrator-migration.md
  - Mark COMPLETE (2026-05-31); historical record only

plan-phase1c-full-reproducibility.md
  - Incus access: direct, not via SOCKS proxy

prompts/builder.md + prompts/adversary.md
  - cc-ci access language only: direct ssh, no proxy restart instructions
  - adversary: *.ci.commoninternet.net via plain curl, no proxy flag

REBOOTS.md
  - Retitle for VM; note Pi retired; Pi entries marked historical

systemd/cc-ci-loops.service
  - User/Group/HOME/PATH: notplants → loops
  - Remove cc-ci-tailscaled.service dependency (no proxy on VM)
  - Add note about nix/configuration.nix as the authoritative VM declaration

test-e2e-testme-acceptance.md
  - tailscale status: no --socket flag
  - ssh to throwaway: no ProxyCommand

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

AGENTS.md

@@ -20,7 +20,7 @@ watches from outside.
 
 **Every time you (the orchestrator) start or resume, send a `PushNotification`** that you are online —
 the operator wants to know the supervising session is back (especially after a reboot, which kills
-this session along with the Pi). Include the current phase and the reboot count. Steps on startup:
+this session). Include the current phase and the reboot count. Steps on startup:
 1. Read `cc-ci-plan/REBOOTS.md` (count the `## Reboots` entries) and `cc-ci-plan/launch.sh status`
    (current phase + whether the loops/watchdog are running).
 2. `PushNotification` (proactive), e.g.: *"cc-ci orchestrator online — phase 2, loops+watchdog
@@ -32,8 +32,8 @@ this session along with the Pi). Include the current phase and the reboot count.
 Reboot resilience is handled by **`cc-ci-loops.service`** (system unit): on boot it logs the reboot
 to `REBOOTS.md` (boot_id-gated) and runs `launch.sh start` with `RESUME_PHASE=1`, so the loops +
 watchdog auto-resume the saved phase. The orchestrator session itself is NOT auto-started — the
-operator reconnects to it (that's why the startup notification matters). The fuller "move the
-orchestrator onto its own VM" plan is parked at `cc-ci-plan/plan-orchestrator-migration.md`.
+operator reconnects to it (that's why the startup notification matters). The VM migration is
+complete; see `cc-ci-plan/plan-orchestrator-migration.md` (historical record).
 
 ## Keep the orchestrator open, under remote-control
 
@@ -71,8 +71,8 @@ cc-ci VM"). The orchestrator is the human's steering wheel; the loops are the en
 
 - `.testenv` (**NOT committed**): Tailscale auth key + Gitea bot creds. Load with
   `set -a; . .testenv; set +a` (never echo the values).
-- **cc-ci:** `ssh cc-ci` (root) tunnels through the persistent userspace-tailscaled SOCKS proxy on
-  `127.0.0.1:1055` (`cc-ci-tailscaled.service`). If down: `sudo systemctl restart cc-ci-tailscaled`.
+- **cc-ci:** `ssh cc-ci` (root) directly — the orchestrator VM is a direct tailnet peer (`100.90.116.4`).
+  No proxy. Key: `~/.ssh/cc-ci-root-ed25519`. If unreachable, check `tailscale status`.
 - **Incus/VM fallback:** mTLS certs at `/srv/incus-terraform-nix-vm-creator/terraform-secrets/`;
   b1 is on the same tailnet (reach via the same proxy). See kickoff "Fallback".
 - **Full credential map + how to use each:** `plan.md` §1.5.