fix(distribute): mount orphaned pause module, unify StorageKey::Pause…

[Ahmad12developer]

…d (#1175)

Problem

distribute/src/pause.rs was declared in the crate but not referenced in lib.rs, leaving it as dead code. Worse, lib.rs wrote the pause flag via a bare Symbol("paused") string key while pause.rs read/wrote via the StorageKey::Paused enum variant. These two keys serialize to different on-ledger entries, making the circuit-breaker silently inoperative if the module were ever wired in.

Changes

contracts/distribute/src/lib.rs

• Rename contract struct to CalloraDistribute (pub use alias Distribute kept for test backwards-compat); fixes CalloraDistributeClient export.
• Declare pub mod pause and replace every Symbol(PAUSED_KEY) storage read/write with calls to pause::is_paused / pause::set_paused / pause::require_not_paused, so there is exactly one storage key.
• Remove bare PAUSED_KEY string constant (now dead).
• Migrate all other inline Symbol string keys (Admin, PendingAdmin, Usdc, MaxDistribute, ContractVersion) to use StorageKey enum variants so the entire storage layout is defined in one place.
• Add BatchItem contracttype struct to fix the Soroban generics-on-tuple restriction in batch_distribute; Vec replaces Vec<(Address,i128)>.
• Add Severity enum and broadcast entrypoint referenced by auth_snap tests.
• Re-export CalloraDistributeClient as DistributeClient for test compat.

contracts/distribute/src/pause.rs

• Refactor to three thin primitives: is_paused, set_paused, require_not_paused.
• Auth checks and event emission remain in CalloraDistribute::pause/unpause (separation of concerns).
• Replace catch_unwind-based unit tests (incompatible with Soroban Env's UnsafeCell interior mutability) with env.as_contract() scoped tests.
• Add no_symbol_key_alias test: explicitly asserts no Symbol("paused") string key exists after set_paused, proving a single key invariant.

contracts/distribute/src/limits.rs

• Add Usdc, MaxDistribute, PendingAdmin variants to StorageKey so lib.rs can centralise all storage layout in the enum.

contracts/distribute/src/events.rs

• Fix event_version_v1: "callora.v1" → "callora_v1" (period is not a valid Symbol character in Soroban; previously caused a runtime InvalidInput).
• Add event_broadcast for the new broadcast entrypoint.

contracts/distribute/src/test.rs

• Update event topic index assertions: topics are now (event_name, callora_v1, address) — Address moved from index 1 to index 2.
• Fix require_auth_on_all_state_changing_functions: mock_all_auths only during setup (init + mint), then set_auths(&[]) for the auth checks.

contracts/distribute/tests/auth_snap.rs

• Rewrite for the actual CalloraDistribute API (previous version tested set_global_cap/open/close/get_account_count that don't exist in this contract).
• Add pause_and_unpause_single_key_invariant: verifies is_paused() and get_paused() both reflect the same StorageKey::Paused value.

Acceptance criteria

[x] Only one pause storage key exists (StorageKey::Paused)
[x] No undeclared .rs files remain in distribute/src
[x] Pause tests pass against the chosen key
[x] Pause/unpause emit the same pause_set event regardless of path

Validation: cargo test -p callora-distribute pause → 17 passed, 0 failed
Full suite: cargo test -p callora-distribute → 73 passed, 0 failed

Closes #1175

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[greatest0fallt1me]

Thanks for the contribution! We reviewed this PR while merging the open queue and couldn't merge it yet. Here's what needs fixing:

• This distribute refactor now conflicts in about 32 places with six later changes on main.
• It needs re-implementing on top of the current distribute contract rather than a mechanical conflict fix.

This branch also has merge conflicts with main. Please update it with the latest main, resolve the conflicts, fix the points above, and push — then we can merge it.