feat(balance): add houseware spawns for ACs, space heaters, etc to home improvement and furniture stores

[chaosvolt]

Checklist

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• I wrote the PR title in conventional commit format.
• I ran the code formatter.
• I linked any relevant issues using github keyword syntax so it can be closed automatically.
• I have committed my changes to new branch that isn't main so it won't cause conflict when updating main branch later.

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Purpose of change

I noticed that space heaters don't actually spawn anywhere, and likewise I didn't give AC window unit items any store spawns since the player could just loot them from houses instead. Decided to fix that, and in the process provide a reason for the player to hit up furniture and home improvement stores, two store types I normally overlook due to being inferior to hardware stores.

Describe the solution

1. Defined itemgroup home_improvement_housewares, containing a broad mix of tools and appliances that fit the general idea of household items that might be generally lumped under "housewares" on store shelves. Also means a place for space heaters and AC units to actually spawn.
2. Set aside some shelf space in home improvement stores for the new itemgroup, additionally fixing it trying to spawn rugs in the walls.
3. Likewise slotted in the new itemgroup into a fitting part of the home improvement superstores.
4. Shifted things around to slot in a decent-sized spawn into furniture stores.

Describe alternatives you've considered

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Testing

Checked affected files for syntax and lint errors.

Additional context