Phase 7: netfox + godot-jolt stack upgrade

Stack installed:
- netfox v1.35.3 (core + extras + noray + internals)
- godot-jolt v0.16.0-stable

Architecture:
- Server: ENet transport (works headless, no netfox deps)
- Client/Editor: netfox rollback (RollbackSynchronizer, TickInterpolator)

New/modified:
- docs/migration-netfox-plan.md — migration architecture
- scripts/network/network_manager.gd — netfox-aware ENet fallback
- scripts/network/player.gd — clean base player
- client/characters/player_netfox.gd — rollback player w/ WeaponManager
- client/characters/input/player_net_input.gd — BaseNetInput subclass
- client/characters/character/fps_character_controller.gd — netfox input feed
- client/weapons/ — weapon data, registry, TacticalWeaponHitscan, WeaponManager
- client/scripts/round_replicator.gd — client-side round state bridge
- server/scripts/round_manager.gd — improved state machine
- server/scripts/plugin_api/plugin_manager.gd — refined plugin system
- config: enemy_tag, ally_tag for meatball targeting

Removed: old C++ SimulationServer GDExtension (replaced by netfox rollback)

addons/netfox/CONTRIBUTORS.md

@@ -0,0 +1,31 @@
+# Contributors
+
+This addon, and the entirety of [netfox] is a shared effort of [Fox's Sake
+Studio], and the community. The following is the list of community contributors
+involved with netfox:
+
+* Alberto Klocker <albertok@gmail.com>
+* Andrew Davis <jonandrewdavis@gmail.com>
+* Bryan Lee <42545742+bryanmylee@users.noreply.github.com>
+* Dan Schuman <danschuman@gmail.com>
+* Dustie <77035922+DustieDog@users.noreply.github.com>
+* Eric Volpone <ericvolpone@gmail.com>
+* Gordon MacPherson <gordon@gordonite.tech>
+* Jake Cattrall <krazyjakee@gmail.com>
+* Jon Stevens <1030863+jonstvns@users.noreply.github.com>
+* Joseph Michael Ware <9at25jnr3@mozmail.com>
+* Matias Kumpulainen <kumpulainen.matias@gmail.com>
+* Nicolas Batty <nicolas.batty@gmail.com>
+* Ricky <77863853+RickyYCheng@users.noreply.github.com>
+* Riordan-DC <44295008+Riordan-DC@users.noreply.github.com>
+* Russ <622740+russ-@users.noreply.github.com>
+* Ryan Roden-Corrent <github@rcorre.net>
+* TheYellowArchitect <dmalandris@uth.gr>
+* TheYellowArchitect <hello@theyellowarchitect.com>
+* camperotactico <alberto.vgdd@gmail.com>
+* gk98s <89647115+gk98s@users.noreply.github.com>
+* zibetnu <9at25jnr3@mozmail.com>
+
+[netfox]: https://github.com/foxssake/netfox
+[Fox's Sake Studio]: https://github.com/foxssake/
+