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/queries/operations.sql

@@ -14,11 +14,6 @@ WHERE (sqlc.narg('state')::text IS NULL OR sig.state = sqlc.narg('state'))
 ORDER BY se.slug
 LIMIT sqlc.arg('lim');
 
--- name: ListEntityStatus :many
-SELECT e.slug, e.type, st.health, st.last_check_at
-FROM entity_status st JOIN entities e ON e.id = st.entity_id
-ORDER BY e.slug;
-
 -- name: GetIdempotentResponse :one
 SELECT response_code, response_body, request_hash FROM idempotency_keys
 WHERE actor = $1 AND key = $2;
@@ -89,9 +84,6 @@ DO UPDATE SET occurrence_count = signals.occurrence_count + 1,
               updated_at = now()
 RETURNING *;
 
--- name: UpdateSignalState :exec
-UPDATE signals SET state = $2, updated_at = now() WHERE entity_id = $1;
-
 -- name: GetOpenSignalsForAutoAct :many
 -- Signals with auto-act classifications that haven't been executed yet
 SELECT s.*, c.entity_id AS classification_id, c.action, c.risk_class, c.route,
@@ -106,12 +98,6 @@ WHERE c.route = 'auto-act'
 ORDER BY s.last_seen_at ASC
 LIMIT $1;
 
--- name: InsertClassification :exec
-INSERT INTO classifications (entity_id, signal_entity_id, target_entity_id, action,
-    recommended_action, risk_class, route, blast_radius, pattern_confidence,
-    skill_id, autonomy_check, reasoning, correlation_id)
-VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13);
-
 -- name: ListClassifications :many
 SELECT c.entity_id, c.signal_entity_id, c.target_entity_id, c.action,
        c.recommended_action, c.risk_class, c.route, c.blast_radius,
@@ -153,11 +139,6 @@ WHERE (sqlc.narg('status')::text IS NULL OR e.status = sqlc.narg('status'))
 ORDER BY te.slug
 LIMIT sqlc.arg('lim');
 
--- name: InsertFeedback :exec
-INSERT INTO feedback (entity_id, execution_id, outcome, observation, lesson,
-    unexpected_side_effects, tags)
-VALUES ($1, $2, $3, $4, $5, $6, $7);
-
 -- name: GetFeedbackAfterWatermark :many
 SELECT f.entity_id, f.execution_id, f.outcome, f.observation, f.lesson,
        f.unexpected_side_effects, f.tags, f.created_at,
@@ -201,11 +182,6 @@ SELECT * FROM skills
 WHERE (sqlc.narg('status')::text IS NULL OR status = sqlc.narg('status'))
 ORDER BY name, version DESC;
 
--- name: InsertSkill :exec
-INSERT INTO skills (entity_id, version, name, procedure, applies_type, action,
-    pattern_ids, status, changed_by, change_reason)
-VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10);
-
 -- name: UpdateSkillStatus :exec
 UPDATE skills SET status = $2, last_used_at = now() WHERE entity_id = $1 AND version = $2;