PGx CN: pgx copy-number train|call (CLI-031/032, PCN-001..017, IN-050), region BED v1, demo identities (K-028)

- simurg/pgx/cn.py: per-region CN mixture, mu_c = delta + gamma*log2((c+1)/3), free lower CN-0 component,
  Hardy-Weinberg-constrained weights over haplotype copy numbers, EM from a grid of label starts.
- pipeline/pgx_cn.py: model file (.simurg-pgxcn), batch rules (PCN-004), per-sample CN VCF + tbi, batch and
  sample summaries.
- The GSA v4 PGx demo arrays are 30 CEPH/1000G individuals (scripts/pgx/demo36_identity.tsv); against NYGC 30x
  SV RD_CN 224/240 region calls agree (GSTM1, UGT2B17 30/30), in-sample (docs/validation/V2_pgx_cn.md).

src/simurg/core/errors.py

@@ -151,6 +151,26 @@ CATALOGUE: dict[str, MessageDef] = dict(
         _m("E_CN_SIDECAR_MISSING", "error", "cn_call_manifest.json not found in the cn call output", "CYTO-032"),
         _m("E_CN_VCF_UNINDEXED", "error", "CNV VCFs must be bgzipped and indexed for annotate", "CYTO-032"),
         _m("E_CN_FAILED", "error", "CN calling failed for the sample", "CYTO-040"),
+        # --- targeted PGx copy number (PCN-001 .. PCN-017) ---------------------------------------------------
+        _m("E_PGX_BATCH_TOO_SMALL", "error", "Too few (passing) samples in the batch for PGx CN calling", "PCN-004"),
+        _m("W_PGX_BATCH_BELOW_RECOMMENDED", "warning", "Fewer passing samples than recommended", "PCN-004"),
+        _m("E_PGX_TRAIN_TOO_SMALL", "error", "Too few (passing) samples to train a PGx CN model", "PCN-005"),
+        _m(
+            "E_MODEL_CLUSTER_MISMATCH",
+            "error",
+            "Input GTCs were called with another cluster file than the model",
+            "IN-050",
+        ),
+        _m(
+            "W_MODEL_CLUSTER_MISMATCH",
+            "warning",
+            "Input GTCs were called with another cluster file than the model",
+            "IN-050",
+        ),
+        _m("W_PGX_REGION_FEW_PROBES", "warning", "PGx CN region has fewer than 10 unmasked probes", "PCN-008"),
+        _m("W_PGX_NO_ALT_CONTIG", "warning", "FASTA lacks a contig carrying a PGx region; REF written as N", "IN-062"),
+        _m("W_PGX_BATCH_COMPOSITION", "warning", "Batch spans several lots/batches or > 14 days of scans", "PCN-006"),
+        _m("E_PGX_CN_FAILED", "error", "PGx CN calling failed for the sample", "PCN-002"),
         # --- methylation control QC (MET-001 .. MET-018) -------------------------------------------------
         _m("E_METH_NO_ASSAY", "error", "Probe section not found", "MET-002"),
         _m("E_METH_NO_CONTROLS", "error", "Missing control probes in manifest", "MET-002"),