Unhelpful behaviour when assembling ammo belts from linkages

# Describe the bug

When you (a)ctivate a pile of linkages and select a pile of ammo you can end up with an ammo belt with only one bullet.

# Steps To Reproduce

1. Place a pile of links on the ground (I used .223 ammo belt linkages x 548)
2. Place a pile of suitable ammo on the ground (5.56 NATO M855A1 x 1782)
3. (a)ctivate, select linkages then select ammo.
4. Note that your belt is (1/500 .223)

# Expected behavior

It would be nice if you were smart enough to include 500 linkages before starting to assembly.

NOTE: This works perfectly fine as long as you have the 500 linkages in your inventory, not selected from the ground.

# Versions and configuration

- OS: Windows x64 8.1
- Game Version: 0.E-8914-g8c0034b-dirty [64-bit]
- Graphics Version: Tiles
- Game Language: English [en]
- Mods loaded: [
Dark Days Ahead [dda],
Disable NPC Needs [no_npc_food],
Bionic Professions [package_bionic_professions],
No Fungal Monsters [No_Fungi],
Stats Through Skills [StatsThroughSkills],
SpeedyDex [speedydex],
Stats Through Kills [stats_through_kills]
]

Start by reproducing the linkage-and-ammo activation sequence described in the issue, comparing ground piles with linkages already in inventory. Trace the ammo-belt assembly entry point and verify that selecting ground linkages uses the available quantity; done means the example produces a belt with the expected number of rounds rather than one.

Written by the indexing model from the issue text.