feat: stage 2, the NPC and its API (API 2)

RunicNPC now spawns its own NPC: Rust's scientist with its ScientistNPC and
ScientistBrain swapped for ours, copying a fixed field list generated from
Rust's unmodified assembly (D232, tools/fieldlist). Profiles live in
data/RunicNPC/profiles.json in the approved shape (D238); placements persist
with each/group respawn (D236) and wait for a missing profile or route
(D237); roamers wander, follow Rust's monument paths, or walk a route (D233,
D234), with our own chase where Rust's needs an AI zone; sentries hold their
spot; NPCs walk home and sleep past 160 m of any player (D235). Spawns wait
for the navmesh and are spread over frames; caps are off by default and the
cost warning is shown instead (D227). The whole PLAN.md section 4 API and its
hooks are in, documented in docs/runicnpc/API.md.

tools/RunicNpcTest.cs is the stage 2 harness; every group passed on both
rigs, and after a plugin reload and a server restart. checkPlugin no longer
counts an override (RunicNpcPlayer.OnDied) as a hook.

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

plugin.toml

@@ -22,8 +22,9 @@
 # a RunicNPC too old for the bridge it is pairing with. Declaring it here is what
 # lets a bundle check the pair BEFORE an operator installs it.
 #
-# Current: 1 — `RunicNpc_ApiVersion()` and nothing else (stage 0).
-api = 1
+# 1 was stage 0's: `RunicNpc_ApiVersion()` and nothing else.
+# Current: 2 — stage 2's whole API, PLAN.md §4, documented in docs/runicnpc/API.md.
+api = 2
 
 # ── Framework floors ─────────────────────────────────────────────────────────
 #