feat(simulation): implement economics integration sprint — #810 #821 #822 #823

Implements the full D-180/D-181 economics pipeline:

**#810 — Event input port (D-180)**
- Add EconEvent struct with Target/Effect/Duration/Visibility variants
- Implement EventPort as typed input queue for external disruptions
- Apply events in simulation step; D-179 Test 3 now uses real shock injection

**#821 — Integrate econ-sim into server tick loop**
- Extract econ-sim as library crate (lib.rs + sim.rs, Cargo.toml [lib] section)
- Add Simulation stateful runner; step() advances one economy tick
- Add EconSimResource, EconStateResource (7 D-181 signals), tick_economy_simulation
- Economy loads once at startup; graceful no-op when systems.db absent
- Server advances economy 1 tick per 10 game ticks (D-031)

**#822 — Expose economy state over IPC bridge**
- Protocol version 20 → 21
- Add EconomySnapshot, EconNodeSnapshot wire types
- Add EconStateQuery PlayerAction variant; response in economy_snapshot field
- Add EconQueryBuffer resource + serve_econ_state_query system

**#823 — Economics debug commands**
- Add InjectEconEvent, SetEconParam, GetEconState to DebugCommandKind
- Add EconDebugEffect, EconParamKind enums
- SetEconParam mutates α/β at runtime (α/β promoted to pub const + Simulation fields)
- ALPHA and BETA constants threaded through step_inner/trade_step signatures

All 1147 unit tests pass; zero warnings.

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

server/Cargo.lock

@@ -570,6 +570,17 @@ version = "2.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "117240f60069e65410b3ae1bb213295bd828f707b5bec6596a1afc8793ce0cbc"
 
+[[package]]
+name = "econ-sim"
+version = "0.1.0"
+dependencies = [
+ "clap",
+ "rand",
+ "rand_chacha",
+ "rusqlite",
+ "serde",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -1245,13 +1256,14 @@ dependencies = [
 
 [[package]]
 name = "settled-reach-server"
-version = "0.1.32"
+version = "0.1.33"
 dependencies = [
  "bevy_app",
  "bevy_ecs",
  "bincode",
  "clap",
  "crossbeam-channel",
+ "econ-sim",
  "pathfinding",
  "rand",
  "rand_chacha",