[Customized] Allow the aircraft to enter area guard mission and not crash immediately without any airport (#1844)

- When a `guard` command (`[G]` by default) or a `area guard` command
(`[Ctrl]+[Alt]`) is issued, the aircraft will search for targets around
the position (for `guard` is the current location, for `area guard` is
the target position) and return immediately when ammos are depleted.
- If the target is not found, or if there is still ammo when the target
is destroyed, it will continue to hover over the guarded area.
- `ExtendedAircraftMissions.FastScramble` controls whether the aircraft
can scramble when its airport has been destroyed.
- `ExtendedAircraftMissions.UnlandDamage` controls the damage suffered
by the aircraft every 4 frames when there is no airport for the aircraft
to land. If the value is negative, it will crash immediately. Not
recommended to use when `ExtendedAircraftMissions` is not enabled.


In `rulesmd.ini`:
```ini
[General]
ExtendedAircraftMissions.UnlandDamage=-1  ; integer

[SOMEAIRCRAFT]                            ; AircraftType
ExtendedAircraftMissions.FastScramble=    ; boolean, default to [General] -> ExtendedAircraftMissions
ExtendedAircraftMissions.UnlandDamage=    ; integer, default to [General] -> ExtendedAircraftMissions.UnlandDamage
```


![飞机守卫](https://github.com/user-attachments/assets/7ed4c69c-e5e7-41f6-97d6-8f45d910adb3)

Author: CrimRecya

CREDITS.md

@@ -545,6 +545,7 @@ This page lists all the individual contributions to the project by their author.
   - Fix for pathfinding crashes on big maps due to too small pathfinding node buffer
   - Fix an issue that units' `LaserTrails` will always lags behind by one frame
   - Fix an issue that the currently hovered planning node not update up-to-date, such as using hotkeys to select technos
+  - Allow the aircraft to enter area guard mission and not crash immediately without any airport
 - **Ollerus**:
   - Build limit group enhancement
   - Customizable rocker amplitude

docs/Fixed-or-Improved-Logics.md

@@ -325,24 +325,29 @@ FiringForceScatter=true   ; boolean
 ### Extended Aircraft Missions
 
 - Aircraft will now be able to use waypoints.
-- When a `guard` command (`[G]` by default) is issued, the aircraft will search for targets around the current location and return immediately when target is not found, target is destroyed or ammos are depleted.
-  - If the target is destroyed but ammos are not depleted yet, it will also return because the aircraft's command is one-time.
+- When a `guard` command (`[G]` by default) or a `area guard` command (`[Ctrl]+[Alt]`) is issued, the aircraft will search for targets around the position (for `guard` is the current location, for `area guard` is the target position) and return immediately when ammos are depleted.
+  - If the target is not found, or if there is still ammo when the target is destroyed, it will continue to hover over the guarded area.
 - When an `attack move` command (`[Ctrl]+[Shift]`) is issued, the aircraft will move towards the destination and search for nearby targets on the route for attack. Once ammo is depleted or the destination is reached, it will return.
   - If the automatically selected target is destroyed but ammo is not depleted yet during the process, the aircraft will continue flying to the destination.
 - In addition, the actions of aircraft are also changed.
   - `ExtendedAircraftMissions.SmoothMoving` controls whether the aircraft will return to the airport when the distance to the destination is less than half of `SlowdownDistance` or its turning radius.
   - `ExtendedAircraftMissions.EarlyDescend` controls whether the aircraft not have to fly directly above the airport before starting to descend when the distance between the aircraft and the landing point is less than `SlowdownDistance` (also work for aircraft spawned by aircraft carriers).
   - `ExtendedAircraftMissions.RearApproach` controls whether the aircraft should start landing at the airport from the opposite direction of `LandingDir`.
+  - `ExtendedAircraftMissions.FastScramble` controls whether the aircraft can scramble when its airport has been destroyed.
+  - `ExtendedAircraftMissions.UnlandDamage` controls the damage suffered by the aircraft every 4 frames when there is no airport for the aircraft to land. If the value is negative, it will crash immediately. Not recommended to use when `ExtendedAircraftMissions` is not enabled.
 
 In `rulesmd.ini`:
 ```ini
 [General]
-ExtendedAircraftMissions=false          ; boolean
-
-[SOMEAIRCRAFT]                          ; AircraftType
-ExtendedAircraftMissions.SmoothMoving=  ; boolean, default to [General] -> ExtendedAircraftMissions
-ExtendedAircraftMissions.EarlyDescend=  ; boolean, default to [General] -> ExtendedAircraftMissions
-ExtendedAircraftMissions.RearApproach=  ; boolean, default to [General] -> ExtendedAircraftMissions
+ExtendedAircraftMissions=false            ; boolean
+ExtendedAircraftMissions.UnlandDamage=-1  ; integer
+
+[SOMEAIRCRAFT]                            ; AircraftType
+ExtendedAircraftMissions.SmoothMoving=    ; boolean, default to [General] -> ExtendedAircraftMissions
+ExtendedAircraftMissions.EarlyDescend=    ; boolean, default to [General] -> ExtendedAircraftMissions
+ExtendedAircraftMissions.RearApproach=    ; boolean, default to [General] -> ExtendedAircraftMissions
+ExtendedAircraftMissions.FastScramble=    ; boolean, default to [General] -> ExtendedAircraftMissions
+ExtendedAircraftMissions.UnlandDamage=    ; integer, default to [General] -> ExtendedAircraftMissions.UnlandDamage
 ```
 
 ### Fixed spawn distance & spawn height for airstrike / SpyPlane aircraft

docs/Whats-New.md

@@ -10,7 +10,7 @@ You can use the migration utility (can be found on [Phobos supplementaries repo]
 
 ### From vanilla
 
-- Map trigger action `125 Build At...` now plays buildup by default if available, this can be toggled off using the third parameter (values other than 0). See [required changes for `fadata.ini`](#for-map-editor-final-alert-2) on how to enable the parameter in map editor. 
+- Map trigger action `125 Build At...` now plays buildup by default if available, this can be toggled off using the third parameter (values other than 0). See [required changes for `fadata.ini`](#for-map-editor-final-alert-2) on how to enable the parameter in map editor.
 - `IsSimpleDeployer` units now obey deploying facing constraint even without deploying animation. To disable this, set `DeployDir` (defaults to `[AudioVisual] -> DeployDir`) to -1.
 - `Vertical=true` projectiles now default to completely downwards initial trajectory/facing regardless of if their projectile image has `Voxel=true` or not. This behavior can be reverted by setting `VerticalInitialFacing=false` on projectile in `rulesmd.ini`.
 - `Vertical=true` projectiles no longer move horizontally if fired by aircraft by default. To re-enable this behaviour set `Vertical.AircraftFix=false` on the projectile.
@@ -446,6 +446,7 @@ New:
 - Randomized anims for several behaviors (by Ollerus)
 - Shield respawn animation and weapon (by Ollerus)
 - Customize the chained damage of the wall (by TaranDahl)
+- Allow the aircraft to enter area guard mission and not crash immediately without any airport (by CrimRecya)
 
 Vanilla fixes:
 - Fixed sidebar not updating queued unit numbers when adding or removing units when the production is on hold (by CrimRecya)