sharing 2/4: transfer runtime (controllers, economy boundary, gadget swap)

[keithharvey]

📚 Stacked split of #5704 — review bottom-up

• 1/4 · Foundations (modes, economy boundary, transfer library) (sharing 1/4: foundations (modes, economy boundary, transfer library) #7962)
• 2/4 · Transfer runtime (controllers, economy boundary, gadget swap) (sharing 2/4: transfer runtime (controllers, economy boundary, gadget swap) #7963) ← you are here
• 3/4 · Tech Core / Keystone (sharing 3/4: Tech Core / Keystone #7964)
• 4/4 · Sharing Tab UI (sharing 4/4: Sharing Tab UI #7965)

Each PR merges into the one below it; all four squash-equal the sharing_tab branch (verified byte-identical).

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Stack 2 of 4 splitting #5704. Builds on 1/4.

The behavior switch. Replaces the old sharing/restriction gadgets with two unified controllers and routes all team-resource reads/writes through the GG economy boundary.

• add game_resource_transfer_controller (defines GG.GetTeamResources/AddTeamResource/SetTeamShareLevel) and game_unit_transfer_controller
• add cmd_take, allied unit reclaim / partial resurrection / ally geo-mex modes; rename game_disable_assist_ally → game_allied_assist_mode
• delete game_tax_resource_sharing, game_no_share_to_enemy, game_prevent_excessive_share, game_restrict_unit_sharing, game_disable_unit_sharing, game_restrict_resurrection
• migrate all Spring.*TeamResource* call sites to the GG.* boundary
• gadgets/modrules registration, controller spec, in-game test widgets

[github-actions]

Integration Test Results

18 tests  +3   7 ✅ ±0   6s ⏱️ +2s
 1 suites ±0   8 💤 ±0 
 1 files   ±0   3 ❌ +3 

For more details on these failures, see this check.

Results for commit 7f9a08f. ± Comparison against base commit 4c65388.

♻️ This comment has been updated with latest results.