fix(scheduler): Restore ReducerContext recording for scheduled reducers (#3947)

## Summary

This fixes a regression introduced in commit afe169a ("Fix the issues
with scheduling procedures #3816", Dec 5, 2025) where scheduled reducers
stopped recording their `ReducerContext` to the commitlog.

**Impact:**
- No `inputs` section was written to the commitlog for scheduled
reducers
- The reducer's name, caller, timestamp, and arguments were not
persisted

## Root Cause

The old code in `module_host.rs::call_scheduled_reducer_inner` patched
`tx.ctx` with the `ReducerContext`:

```rust
tx.ctx = ExecutionContext::with_workload(
    tx.ctx.database_identity(),
    Workload::Reducer(ReducerContext { ... }),
);
```

This was removed when the logic moved to `scheduler.rs`. The new code in
`call_reducer_with_tx` only applies the `ReducerContext` when `tx` is
`None` — since the scheduler passes `Some(tx)`, the context was never
applied.

## Fix

Restore the `tx.ctx` patching in `scheduler.rs` before calling
`call_reducer_with_tx`.

## Test Plan

- [ ] Existing tests pass

Co-authored-by: Phoebe Goldman <phoebe@clockworklabs.io>

Author: Ludv1gL

crates/core/src/host/scheduler.rs

@@ -11,7 +11,7 @@ use core::time::Duration;
 use futures::{FutureExt, StreamExt};
 use rustc_hash::FxHashMap;
 use spacetimedb_client_api_messages::energy::EnergyQuanta;
-use spacetimedb_datastore::execution_context::Workload;
+use spacetimedb_datastore::execution_context::{ExecutionContext, ReducerContext, Workload};
 use spacetimedb_datastore::locking_tx_datastore::MutTxId;
 use spacetimedb_datastore::system_tables::{StFields, StScheduledFields, ST_SCHEDULED_ID};
 use spacetimedb_datastore::traits::IsolationLevel;
@@ -394,7 +394,7 @@ pub(super) async fn call_scheduled_function(
         })
     };
 
-    let tx = db.begin_mut_tx(IsolationLevel::Serializable, Workload::Internal);
+    let mut tx = db.begin_mut_tx(IsolationLevel::Serializable, Workload::Internal);
 
     // Determine the call params.
     // This also lets us know whether to call a reducer or procedure.
@@ -418,6 +418,24 @@ pub(super) async fn call_scheduled_function(
     // so we must remove the schedule row before executing.
     match params {
         CallParams::Reducer(params) => {
+            // Patch the transaction context with ReducerContext so the commitlog
+            // records the reducer's name, caller, timestamp, and arguments.
+            //
+            // Background: Scheduled reducers start with Workload::Internal, but
+            // call_reducer_with_tx only sets ReducerContext when tx is None.
+            // Since we pass Some(tx), we must set it here.
+            let reducer_name = &*module_info.module_def.reducer_by_id(params.reducer_id).name;
+            tx.ctx = ExecutionContext::with_workload(
+                tx.ctx.database_identity(),
+                Workload::Reducer(ReducerContext {
+                    name: reducer_name.into(),
+                    caller_identity: params.caller_identity,
+                    caller_connection_id: params.caller_connection_id,
+                    timestamp: params.timestamp,
+                    arg_bsatn: params.args.get_bsatn().clone(),
+                }),
+            );
+
             // We don't want a panic in the module host to affect the scheduler, as unlikely
             // as it might be, so catch it so we can handle it "gracefully". Panics will
             // print their message and backtrace when they occur, so we don't need to do