refactor: sqlc vs raw SQL — hybrid approach (R3)

Deleted 8 genuinely unused sqlc queries (no inline equivalent):
- UpsertCurrentRelationship, ListEntitiesCapped, ListEntityStatus,
  UpdateSignalState, InsertClassification, InsertFeedback, InsertSkill,
  UpsertCurrentRelationship — all had zero call sites.

Migrated 9 inline raw SQL sites to use sqlc queries:
- GetOntology (impl.go): ListEntityTypes, ListRelationshipTypes,
  ListLifecycleDefs — replaces 3 raw pool.Query blocks with typed sqlcgen
  calls, eliminating manual row scanning.
- EndRelationship (phase3.go): EndCurrentRelationship — replaces tx.Exec
  with sqlcgen.New(tx).EndCurrentRelationship.
- checkPrecondition (impl.go): GetEntityStatus — replaces tx.QueryRow +
  manual Scan with sqlcgen.New(tx).GetEntityStatus.
- GetEntityRelations (impl.go): ListEntityRelations — replaces raw pool.Query
  + scanRelationships helper (now deleted).
- GetGraph (impl.go): ListGraphEdges — replaces raw pool.Query +
  scanRelationships.
- resolveEntityID (impl.go): GetEntityBySlug/GetEntityByID — replaces
  raw pool.QueryRow + Scan.
- createApproval (mcp/server.go): InsertApproval — replaces raw pool.Exec
  with sqlcgen.InsertApproval.

Deleted scanRelationships helper (was only used by the two migrated
graph queries above).

Regenerated sqlcgen — also picks up stale model updates (AgentSession,
SessionPlanStep, SessionQuestion, etc. from recent migrations).

Documented the carve-out in .agents/dev/CONTRIBUTING.md §SQL conventions:
sqlc is the default; raw pool.Query/Exec is reserved for LISTEN/NOTIFY,
dynamic WHERE builders, blast_radius(), and COPY.

go vet, build, httpapi/mcp/db tests all pass. -383/+170 lines.

internal/db/sqlcgen/models.go

@@ -35,11 +35,17 @@ type AgentMessage struct {
 }
 
 type AgentSession struct {
-	ID           uuid.UUID
-	Title        string
-	Actor        string
-	CreatedAt    time.Time
-	LastActiveAt time.Time
+	ID               uuid.UUID
+	Title            string
+	Actor            string
+	CreatedAt        time.Time
+	LastActiveAt     time.Time
+	Goal             string
+	Status           string
+	Outcome          *string
+	Summary          string
+	EntityID         *uuid.UUID
+	CompletionNudges int32
 }
 
 type Approval struct {
@@ -83,6 +89,7 @@ type AuditLog struct {
 	Detail        []byte
 	SourceIp      *string
 	CorrelationID *string
+	SessionID     *uuid.UUID
 }
 
 type AutonomySetting struct {
@@ -289,6 +296,13 @@ type MetricSample struct {
 	Tags     []byte
 }
 
+type NomosPlanExecution struct {
+	ExecutionID uuid.UUID
+	SessionID   uuid.UUID
+	ContinuedAt *time.Time
+	CreatedAt   time.Time
+}
+
 type Pattern struct {
 	EntityID        uuid.UUID
 	AppliesType     string
@@ -351,6 +365,32 @@ type SeedVersion struct {
 	AppliedAt   time.Time
 }
 
+type SessionPlanStep struct {
+	ID          uuid.UUID
+	SessionID   uuid.UUID
+	Seq         int32
+	Title       string
+	Detail      string
+	Status      string
+	ExecutionID *uuid.UUID
+	TargetSlug  *string
+	StartedAt   *time.Time
+	FinishedAt  *time.Time
+	CreatedAt   time.Time
+	Generation  int32
+}
+
+type SessionQuestion struct {
+	ID         uuid.UUID
+	SessionID  uuid.UUID
+	Prompt     string
+	Context    []byte
+	Status     string
+	Answer     *string
+	CreatedAt  time.Time
+	AnsweredAt *time.Time
+}
+
 type Signal struct {
 	EntityID        uuid.UUID
 	Kind            string