The catalogue had grown a barracks, wartime shelters, an air-defense
battery, a warm-water port and a shipyard, but only as data: infantry
still trained without a barracks, shelters did nothing, and an airport was
just an airbase. Each building now names the rule it grants with a
`mechanic` id, so the simulation and the city panel describe the same
thing without magic strings.
- Barracks and shipyards open one more production line each. A line sticks
to one entry at full rate, so two units build at once rather than the
head absorbing every line; the base behaviour (one queue, overflow
carrying into the next entry) is unchanged.
- Wartime shelters keep 10% of civilians per level safe from bombardment
and are very hard to knock down, and ranged fire can now destroy a
building level outright, with no refund. Each building rolls its own
chance per point of damage, from a generator seeded off the world so a
bombardment replays identically.
- Air defense fires one volley at a hostile aircraft the moment it enters
the city tile, scaled by its level; a plane shot down never drops its
bombs.
- A port adds 1000 GDP per capita per level, per adjacent sea tile, to
every tile in its region.
- An airport draws a daily trickle of people from every other airport city
in the world, scaled by the destination's level.
- Wired the new effects into the city panel and taught the repeatable
Industrial Automation to satisfy other technologies' prerequisites.
Added tests for each mechanic and for the parallel lines.