feat(loader): InstrumentFilter::FrontMonth for cross-quarter ES.FUT data

Replaces Option<u32> instrument_id_filter with InstrumentFilter enum {All,
Id(u32), FrontMonth}. FrontMonth runs a two-pass detect over the DBN
stream: pass 1 counts instrument_ids and collects SymbolMapping records,
picks the dominant id, validates it resolves to an ES contract via regex
ES[FGHJKMNQUVXZ]\d{1,2}; pass 2 streams the filtered records.

Motivated by alpha-perception-k54wd: a single-id filter on parent-symbol
ES.FUT data caught Q1 2024 (kept=73M) but kept=0 for Q2-Q9 because ES
front-month rolls quarterly (ESH4 -> ESM4 -> ESU4 -> ESZ4 ...). FrontMonth
self-tunes across the rolls without needing a per-file id table.

Sidecar keys distinguish modes: mbp10 / mbp10_instr<id> / mbp10_front_month.
CLI flag renamed --instrument-id -> --instrument-mode {all,id=N,front-month}
with matching parameter rename in argo-alpha-perception.sh + template.

crates/ml/examples/alpha_dqn_h600_smoke.rs

@@ -172,7 +172,10 @@ impl Drop for MappedF32 {
     }
 }
 
-use data::providers::databento::{dbn_parser::DbnParser, mbp10::Mbp10Snapshot};
+use data::providers::databento::{
+    dbn_parser::{DbnParser, InstrumentFilter},
+    mbp10::Mbp10Snapshot,
+};
 use ml::cuda_pipeline::alpha_isv_slots::{
     ACTION_ENTROPY_EMA_INDEX, ALPHA_ISV_BLOCK_LO, EARLY_Q_MOVEMENT_EMA_INDEX,
     Q_SPREAD_EMA_INDEX, RANDOM_BASELINE_MEAN_INDEX, RANDOM_BASELINE_STD_INDEX,
@@ -391,7 +394,7 @@ fn load_snapshots(
     let mut rows: Vec<SnapshotRow> = Vec::with_capacity(max_snapshots);
     'files: for file in &files {
         let mut hit_limit = false;
-        let result = parser.parse_mbp10_streaming(file, snapshot_interval, None, |snap: &Mbp10Snapshot| {
+        let result = parser.parse_mbp10_streaming(file, snapshot_interval, InstrumentFilter::All, |snap: &Mbp10Snapshot| {
             if rows.len() >= max_snapshots {
                 hit_limit = true;
                 return;

crates/ml/examples/alpha_fit_fill_model.rs

@@ -40,7 +40,7 @@ use clap::Parser;
 use tracing::{info, warn};
 
 use data::providers::databento::{
-    dbn_parser::DbnParser,
+    dbn_parser::{DbnParser, InstrumentFilter},
     mbp10::Mbp10Snapshot,
 };
 
@@ -163,7 +163,7 @@ fn main() -> Result<()> {
         let result = parser.parse_mbp10_streaming(
             file,
             cli.snapshot_interval,
-            None,
+            InstrumentFilter::All,
             |snap: &Mbp10Snapshot| {
                 if n_processed >= limit {
                     hit_limit = true;

crates/ml/examples/alpha_random_baseline.rs

@@ -35,7 +35,7 @@ use clap::Parser;
 use tracing::{info, warn};
 
 use data::providers::databento::{
-    dbn_parser::DbnParser,
+    dbn_parser::{DbnParser, InstrumentFilter},
     mbp10::Mbp10Snapshot,
 };
 use ml::env::action_space::N_ACTIONS;
@@ -168,7 +168,7 @@ fn main() -> Result<()> {
     'files: for file in &files {
         let mut hit_limit = false;
         let result =
-            parser.parse_mbp10_streaming(file, cli.snapshot_interval, None, |snap: &Mbp10Snapshot| {
+            parser.parse_mbp10_streaming(file, cli.snapshot_interval, InstrumentFilter::All, |snap: &Mbp10Snapshot| {
                 if rows.len() >= cli.max_snapshots {
                     hit_limit = true;
                     return;

crates/ml/examples/precompute_features.rs

@@ -580,7 +580,7 @@ async fn main() -> Result<()> {
                     // precompute_features is the multi-symbol feature-cache
                     // builder; it intentionally consumes every instrument in
                     // each file. No filter.
-                    match ml::features::predecoded::load_or_predecode_mbp10(file, &predecoded_dir, None) {
+                    match ml::features::predecoded::load_or_predecode_mbp10(file, &predecoded_dir, data::providers::databento::dbn_parser::InstrumentFilter::All) {
                         Ok(snapshots) => {
                             info!(
                                 "  {} -> {} snapshots",

crates/ml/src/trainers/dqn/data_loading.rs

@@ -314,7 +314,7 @@ impl DQNTrainer {
         if !self.hyperparams.mbp10_data_dir.is_empty() {
             use crate::features::ofi_calculator::OFICalculator;
             use crate::features::trades_loader::get_trades_for_bar;
-            use data::providers::databento::dbn_parser::DbnParser;
+            use data::providers::databento::dbn_parser::{DbnParser, InstrumentFilter};
 
             let mbp10_dir = Path::new(&self.hyperparams.mbp10_data_dir);
             if mbp10_dir.exists() {
@@ -336,10 +336,10 @@ impl DQNTrainer {
                                 Err(e) => { warn!("  DBN parser init failed: {e}"); return None; }
                             };
                             let mut snapshots = Vec::new();
-                            // DQN data loading predates the instrument-filter
-                            // refactor; keep legacy all-instruments behavior
-                            // until the DQN trainer needs filtering.
-                            match parser.parse_mbp10_streaming(file, 100, None, |snap| {
+                            // DQN data loading keeps legacy all-instruments
+                            // behavior; switch to FrontMonth when DQN training
+                            // moves to multi-quarter walk-forward.
+                            match parser.parse_mbp10_streaming(file, 100, InstrumentFilter::All, |snap| {
                                 snapshots.push(snap.clone());
                             }) {
                                 Ok(_) => {