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/src/simulation/input.rs

@@ -4,6 +4,7 @@
 
 use crate::bridge::debug::DebugCommandBuffer;
 use crate::bridge::types::{FacingDirection, ObjectType, PlayerAction, PlayerInput};
+use crate::simulation::economy::EconQueryBuffer;
 use crate::knowledge::{EntityRegistry, StableId};
 use crate::perception::vision_cone::{facing_from_delta, Facing};
 use crate::settings::{SettingsCommand, SettingsCommandBuffer};
@@ -102,6 +103,7 @@ pub fn process_player_input(
     mut save_load: Option<ResMut<SaveLoadPending>>,
     mut debug_cmd_buffer: Option<ResMut<DebugCommandBuffer>>,
     mut settings_cmd_buffer: Option<ResMut<SettingsCommandBuffer>>,
+    mut econ_query_buf: Option<ResMut<EconQueryBuffer>>,
     door_states: Query<&DoorState>,
     object_types: Query<&ObjectType>,
 ) {
@@ -127,6 +129,7 @@ pub fn process_player_input(
                     | PlayerAction::ChangeSetting { .. }
                     | PlayerAction::RequestAllSettings
                     | PlayerAction::DeleteSetting { .. }
+                | PlayerAction::EconStateQuery { .. }
             )
         {
             continue;
@@ -410,6 +413,13 @@ pub fn process_player_input(
                     );
                 }
             }
+            PlayerAction::EconStateQuery { system_id } => {
+                if let Some(ref mut buf) = econ_query_buf {
+                    buf.pending = Some(system_id);
+                } else {
+                    tracing::debug!("EconStateQuery received but EconQueryBuffer not registered — economy not loaded");
+                }
+            }
         }
     }