feat: rework modules, items and fuel

docs/MODULES.md

@@ -48,7 +48,6 @@ Examples:
 - no docking module means no docking service
 - no habitat module means no population growth or human transport
 - no refinery module means no refining
-- no fuel-processing module means no gas-to-fuel conversion
 - no storage module means reduced or absent inventory capability
 - no shipyard-related module means no ship production
 
@@ -92,7 +91,6 @@ Likely station-side categories include:
 - storage
 - habitat
 - refinery
-- fuel processing
 - manufacturing
 - shipyard or construction support
 - defense
@@ -141,7 +139,6 @@ Examples:
 - reactor
 - capacitor
 - station power core
-- fuel systems
 
 ### Production Modules
 
@@ -150,7 +147,6 @@ These convert goods into other goods or into built output.
 Examples:
 
 - refinery
-- fuel processor
 - factory
 - shipyard support
 
@@ -198,7 +194,6 @@ They may require:
 - build time
 - power
 - workforce
-- fuel or energy inputs
 - docking or logistics support
 
 This should let stations and ships fail in believable ways when underbuilt or undersupplied.
@@ -219,7 +214,6 @@ Modules should define which item flows an entity can participate in.
 Examples:
 
 - a habitat module enables population support
-- a fuel-processing module consumes gas and produces fuel
 - a refinery consumes raw resources and produces processed goods
 - a storage module determines what volume or class of goods can be held
 - a livestock module participates in the food chain