[bug] milestone-tracker: no mark_missed function — expired milestones stay in Pending/InProgress until the oracle provides an update

[gboigwe]

Summary

The only way a milestone transitions to Missed status is when the oracle calls update_progress after the deadline with a current_value < target_value. There is no admin-callable or permissionless mark_missed(milestone_id) function. If the oracle goes offline (see related issue), stops sending updates, or is throttled, milestones that have clearly expired remain perpetually in Pending or InProgress status with no recourse. This blocks any downstream logic that gates on Missed status.

Fix

Add a permissionless mark_missed function that anyone can call once a milestone is past its deadline:

pub fn mark_missed(env: Env, milestone_id: u64) {
    let mut milestone: Milestone = env.storage().persistent()
        .get(&DataKey::Milestone(milestone_id)).expect("not found");
    if milestone.status == MilestoneStatus::Achieved || milestone.status == MilestoneStatus::Missed {
        panic!("already finalized");
    }
    if env.ledger().timestamp() <= milestone.deadline {
        panic!("deadline has not passed");
    }
    milestone.status = MilestoneStatus::Missed;
    env.storage().persistent().set(&DataKey::Milestone(milestone_id), &milestone);
}