feat(detector): SQL/migration detector + SQL_ENTITY NodeKind (#48)

Adds a SqlMigrationDetector under detector/sql that extracts schema-level
entities (tables, views, schemas) from raw SQL DDL and framework-specific
migration files: Flyway (V*__*.sql), Liquibase (XML + YAML), Alembic
(versions/*.py with alembic/op marker guard), Rails (db/migrate/*.rb),
and Prisma (migrations/*/migration.sql). Path/marker discriminators
prevent false positives on arbitrary .py/.rb/.xml/.yml.

Enum additions:
- NodeKind.SQL_ENTITY (new): schema-level table/view/schema node,
  distinct from the code-level ENTITY (JPA/ORM) kind.
- EdgeKind.REFERENCES_TABLE (new): any node (JPA ENTITY, ORM model,
  raw SQL_ENTITY) -> SQL_ENTITY, pairing with existing ORM detectors.
- EdgeKind.MIGRATES (reused): MIGRATION -> SQL_ENTITY. Unused in
  production code elsewhere; only referenced by ModelCoverageTest.

LayerClassifier: SQL_ENTITY classified as `infra`.

Deterministic output (sorted by id on emit); detector is stateless.
ALTER TABLE ADD COLUMN enriches the owning entity via columns_added
property; did not model columns as child nodes to keep graph size
reasonable. DROP TABLE is skipped with a debug log.

Tests: 16 new tests covering positive paths (raw SQL, Flyway, Alembic,
Liquibase XML, Liquibase YAML, Rails, Prisma), negative paths (plain
.py/.yaml, Alembic path without marker), determinism, and DDL variants
(DROP, CREATE INDEX, ALTER TABLE). Test count 3278 -> 3294.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: aksOps

src/main/java/io/github/randomcodespace/iq/analyzer/LayerClassifier.java

@@ -36,7 +36,8 @@ public class LayerClassifier {
     );
 
     private static final Set<NodeKind> INFRA_NODE_KINDS = Set.of(
-            NodeKind.INFRA_RESOURCE, NodeKind.AZURE_RESOURCE, NodeKind.AZURE_FUNCTION
+            NodeKind.INFRA_RESOURCE, NodeKind.AZURE_RESOURCE, NodeKind.AZURE_FUNCTION,
+            NodeKind.SQL_ENTITY
     );
 
     private static final Set<String> INFRA_LANGUAGES = Set.of(

src/main/java/io/github/randomcodespace/iq/detector/sql/SqlMigrationDetector.java

@@ -0,0 +1,8 @@
+/**
+ * SQL and migration detectors.
+ * <p>
+ * Extracts schema-level entities (tables, views, schemas) from raw SQL DDL and
+ * framework-specific migration files (Flyway, Liquibase, Alembic, Rails, Prisma),
+ * and links migrations to the SQL entities they create or alter.
+ */
+package io.github.randomcodespace.iq.detector.sql;

src/main/java/io/github/randomcodespace/iq/detector/sql/package-info.java

@@ -32,7 +32,8 @@ public enum EdgeKind {
     SENDS_TO("sends_to"),
     RECEIVES_FROM("receives_from"),
     PROTECTS("protects"),
-    RENDERS("renders");
+    RENDERS("renders"),
+    REFERENCES_TABLE("references_table");
 
     private final String value;
 

src/main/java/io/github/randomcodespace/iq/model/EdgeKind.java

@@ -38,7 +38,8 @@ public enum NodeKind {
     MIDDLEWARE("middleware"),
     HOOK("hook"),
     SERVICE("service"),
-    EXTERNAL("external");
+    EXTERNAL("external"),
+    SQL_ENTITY("sql_entity");
 
     private final String value;