Gave the world spies, treaties and nuclear weapons

ROADMAP.md

@@ -71,7 +71,7 @@ simplification worth revisiting. Anything unticked is still open.
       work already done.
 - [x] Repeatable technologies with a 2% cost growth per level, notified without
       flooding the news list.
-- [ ] Repeatable technologies, once researched, get automatically focused again
+- [x] Repeatable technologies, once researched, get automatically focused again
 - [x] Theme tabs (Science / Economy / Society / Military).
 - [x] Technology panel shows the research rate rather than a stockpile.
 - [x] Readable effect text for the military and repeatable effects.
@@ -256,9 +256,109 @@ simplification worth revisiting. Anything unticked is still open.
       economy simulator's index reaches about 500-650 for luxury and 200-230 for
       high-tech) instead of settling; revisit the supply and demand balance of
       the two rarer goods.
-- [ ] A dedicated structure hit-point model for cities and tile improvements
-      (see the `[~]` note above).
 - [ ] Real art for the placeholder "dummy icon" SVGs: `icon_radar.svg`,
       `icon_coastal_cannon.svg`, `icon_chip_foundry.svg`,
       `icon_geothermal_plant.svg`, `icon_offshore_wind_turbines.svg`,
       `icon_wind_turbines.svg`.
+
+### Player interaction 
+- [x] In-game chat
+  - Access by pressing T
+  - Shows a text input field in the bottom center
+  - chat messages are ordered down to up, last to first
+
+- [x] Player list
+  - In the diplomacy tab, show who's in control of a nation: the AI or a player
+  - Show it using an icon: human or computer
+  - Also add a column with the leader's name
+
+- [x] Diplomatic treaties, that can convey custom text
+  - [x] In the diplomacy tab, show currently active and past treaties
+  - [x] Players receiving a treaty proposal get a notification, clicking on it opens the treaty info
+  - [x] Treaties have a "Sign" and "Reject" buttons
+  - [x] The whole world is informed that a treaty is being sought, has been signed or has been rejected
+  - Types of treaty effects:
+    - [x] Peace: stops the state of war between two players. All battles cease, troops in enemy territory immediately move to their closest city.
+        - Stranded troops on islands get teleported back, for now
+        - Going back to war breaks the treaty and warns the player
+    - [x] Alliance: signatory players cannot go to war with each other without breaking the treaty. Attacking a member of an alliance declares war on the entire alliance.
+    - [x] Free trade: all tariffs to 0 between the signatory parties
+    - [x] Give city
+    - [x] Give military materials (cannot gift infantry)
+    - [x] Give resources
+    - [~] Give money
+      - Denominated in any currency. Taken from the giving player's central bank foreign reserves if possible, otherwise, bought from the relevant central bank
+        (simplified: the sum moves straight between the two treasuries, no FX or reserves leg)
+      - Cannot get currency from a central bank from a country at war with you
+    - [x] Joint research
+      -  Each players gets the sum of tech points produced by the signatory parties when they focus tech, except on military technology
+
+### Military
+
+- [x] Better troop management
+  - [x] In the unit stack panel, can select all units of a type at once
+  - [x] Show a table of icons instead of the current list
+- [x] Submarine unit
+  - [x] Invisible to other players unless a naval unit is DIRECTLY adjacent
+- [~] Missiles
+  - [x] One-use units.
+  - [x] Types of missiles
+    - [x] Conventional, 30 tiles range
+    - [x] Nuclear (locked behind nuclear tech), 30 tiles range
+    - [x] ICBM, nuclear (locked behind nuclear tech and space program), reaches any tile
+    (a plain missile carries a conventional warhead unless the player arms it
+    nuclear from the unit panel; the ICBM is nuclear by design)
+- [~] WMDs
+  - [x] Nuclear program
+    - [x] Build uranium enrichment centers in cities
+    - [ ] Foreign intelligence may be warned that you are enriching uranium
+    - [x] Once a uranium enrichment center exists, the nuclear weapons tech is unlocked
+    - [x] Once the technology research is complete, players can choose nuclear payloads
+          in their missiles
+    - [x] Nuclear explosion effects:
+      - [x] -90% population on a tile
+      - [x] All buildings and improvements destroyed, except for bunkers and fortifications
+      - [x] -1000 popularity across the board
+      (any unit caught in the blast is destroyed too)
+- [ ] Stacks must behave as single units when it comes to pathfinding
+  - [ ] Cannot go through neutral third-party territory, allied and at-war territory can be walked through
+- [ ] Airplanes move in straight lines as they are not bound by tiles.
+* [x] Non-melee units such as artillery, airplanes, have an 80 % chance to be destroyed when an enemy attempts to capture them
+
+### Intelligence
+* [ ] Gets its own tab
+  - Move propaganda operations to intelligence
+* [ ] Spy unit
+  - Invisible to all other players, by default
+  - 1 tile-radius vision
+  - Mostly high-tech cost
+  - Can move into enemy territory
+  - [ ] Sabotage action:
+    - Blocks production of on a given tile for a week, performed while in *any* country
+    - Perpetrator is given a choice to try and blame someone else
+    - The victim gets a notification, depending on intelligence and counterintelligence level, someone, or no one, will be blamed.
+      - No way for the player to differentiate between a correct blame assignment or a successful false flag
+  - [ ] City spying
+    - Perpetrator gets a report on a city's status, building levels, etc. Counter-intelligence can make the report contain false information
+  - [ ] Comms spying
+    - Done in the capital of a country
+    - Reveals the N last private messages sent from and to that player
+    - Counter-intelligence may garble the messages, or change the sender and receiver of messages
+* [ ] Counter-intelligence tech
+  - [ ] Extremely expensive
+* [ ] Spy satellites
+  - [ ] New space launch center
+    - Extremely expensive
+    - [ ] allow "send spy satellite" action
+      - Everyone is made aware that a satellite was launched
+  - Reveal a random 2-tile-radius chunk of the map every two days
+
+### Migrations
+
+- [x] Populations cannot migrate from their country to a hostile one
+- [x] Expel [population] prevents that population from moving to the country
+- [x] Migration rate cannot be more than 0,01%/day from the original tile.
+
+### Economics
+- [x] Remove the "1% per day budget increase". A construction site simply tries to get materials at current market prices.
+- [ ] Show that units being trained are gathering resources when the player clicks on training them