🤖 Fix proofreading issues in bevy skills

- Fix `ref` keyword used as variable name in code examples
- Fix "retries next tick" → systems continue on normal schedule
- Fix `State::set()` → `NextState::set()` in upgrade skill
- Fix `SceneRoot` → `WorldAssetRoot` for 0.19 consistency
- Fix Replace lifecycle event description (overwritten, not removed)
- Fix grep patterns (quoting, trailing spaces)
- Remove third-party physics/networking content (not Bevy built-ins)

plugins/bevy/skills/bevy-0.19/references/events-observers.md

@@ -72,7 +72,7 @@ Built-in events observers can watch per component:
 |-------|-------|-------|
 | `Add` | component added where absent | first |
 | `Insert` | any insert (add or replace) | after `Add` |
-| `Replace` | component removed, regardless of replacement | before `Remove` |
+| `Replace` | component value overwritten by a new insert over an existing value | before `Remove` |
 | `Remove` | component removed | after `Replace` |
 | `Despawn` | entity despawned (per component) | last |
 

plugins/bevy/skills/bevy-0.19/references/production-gotchas.md

@@ -74,17 +74,6 @@ Any system that can run both rendered and headless needs this.
 
 Custom `#[relationship]` / `#[relationship_target]` pairs auto-sync via hooks. Do not write observers that manually push/remove entities in the target `Vec<Entity>` — that duplicates what the macro does and desyncs.
 
-## Physics plugins (Avian / Rapier pattern)
-
-- **`CollidingEntities` is not auto-inserted** with `Collider` (Avian3D 0.5). Without adding `CollidingEntities::default()`, collision queries return nothing while the simulation runs fine internally.
-- **Removing `RigidBody` from a parent with `Collider` children** can panic with stale internal-tree indices. Despawn collider children first.
-
-## Shared-world multiplayer (server + client in one process)
-
-- **Server entities carry no visual components.** `SceneRoot`/`Mesh3d`/`Sprite` belong on client-spawned entities only; mixing causes host-vs-remote visual drift and double maintenance.
-- **`run_if(is_server)` gates the system, not the query.** In a shared world, server systems still match client replica entities — queries must filter client markers explicitly.
-- **Shared components race.** Server and client systems in one World share component instances; a client system resetting a timer changes what the server system reads the same frame. Use `Local<T>` for server-side state that must stay independent.
-
 ## Debugging heuristics
 
 1. Invisible things: check normals, visibility hierarchy, far plane (1000), asset cache poisoning, scene-label spawning.