feat: API 4, factions, escort, allies, tether, turrets, kit extras and PVE (stage 5)

Stage 5's behaviour (docs runicnpc/PLAN.md, D253-D272):

- profiles gain faction, relations (exceptions), alertRadius, turrets,
  hurtByPlayers, hurtsPlayers and kitUse, and the guard role; the faction
  table rides in profiles.json, one row per pair, both ways (D254, D268);
- our own sensing and fight beside Rust's design: only the factions a
  profile hunts, within its leash of its anchor (D263), the target made
  Horror for the length of our own shot, and Rust's attack routine;
- shooting back at whoever hurt it (D268), the alert radius (D256), clan,
  team or player allies that are never targeted and are defended with
  what they own (D257), escort as an order that walks home when its
  charge is gone (D269), and a placement's tether through ZoneManager
  (D272);
- turrets: ignore through CanBeTargeted, and always through a Harmony
  patch on the safe-zone sentries for our always NPCs only (D267);
- the kit's extras, each opted into and used up: heal, melee,
  flamethrower, grenades and rockets (D260, D265);
- TruePVE/NextGenPVE answered both ways unless a profile turns a direction
  off, and the opt-out enforced by RunicNPC itself (D261, D271);
- API 4: RunicNpc_Factions, _SetFactions, _Escort, _Ally, _Tether and the
  OnRunicNpcEscortEnded hook; rnpc follow, rnpc.faction and tether=.

Compiled and loaded on both rigs (Oxide and Carbon); the sentry patch
applies on both.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

plugin.toml

@@ -24,9 +24,11 @@
 #
 # 1 was stage 0's: `RunicNpc_ApiVersion()` and nothing else.
 # 2 was stage 2's whole API, PLAN.md §4.
-# Current: 3 — stage 4 (D249): RunicNpc_AddPlacement, _RenamePlacement, _RespawnPlacement and the
-# OnRunicNpcPlacementChanged hook, documented in docs/runicnpc/API.md.
-api = 3
+# 3 was stage 4 (D249): RunicNpc_AddPlacement, _RenamePlacement, _RespawnPlacement and the
+# OnRunicNpcPlacementChanged hook.
+# Current: 4 — stage 5: RunicNpc_Factions, _SetFactions, _Escort, _Ally, _Tether, the profile's stage 5
+# fields, a placement's tether, and the OnRunicNpcEscortEnded hook, documented in docs/runicnpc/API.md.
+api = 4
 
 # ── Framework floors ─────────────────────────────────────────────────────────
 #
@@ -45,6 +47,6 @@ min_carbon_version = "2.0.259"
 # `doctor`, which reports a missing one rather than installing it. The PR check
 # holds this list and the plugin's `// Requires:` lines equal.
 #
-# ZoneManager is NOT listed: a zone tether is optional (PLAN.md §6), and a
-# profile that asks for one on a server without it is refused when it is saved.
+# ZoneManager is NOT listed: a zone tether is optional (PLAN.md §6). A placement
+# or an event step that asks for one on a server without it is refused (D272).
 requires_plugins = ["Kits"]