Revert #574 to restore green main

[davidmaronio]

Reverts #574 to restore a green main

Why: #574 ("feat: emergency pause, milestone withdrawals, and per-campaign tokens") was merged on 2026-07-01 while its own CI was red, and it does not compile. main has been broken ever since, which is why every open stellar PR shows the same errors (fmt/clippy/test) — they all rebase/merge onto a broken main.

The breakage in #574:

• duplicate set_emergency_pause_signers import vs the local fn (E0255)
• missing lifetime on token_client_for_address (E0106)
• Vec::iter_mut in verify_milestone (unsupported by soroban Vec, E0599)
• s == &caller type mismatch in emergency_pause (E0308)
• unused imports Vec, token_client, set_emergency_pause_signers (fail -D warnings)
• ~33 test call-sites missing the new token/uses_milestones fields on both CreateCampaignParams and Campaign (E0063)
• E0277: token: Option<Address> in a #[contracttype] struct is not ScVal-convertible in the pinned soroban-sdk — this one is a real data-model issue, not mechanical.

This revert restores the last green commit (368b0f6). The feature should be re-submitted as a fresh PR with passing CI (the Option<Address> representation needs rethinking so it satisfies #[contracttype]).

cc @logantalen — happy to help get the re-submit green.