feat(P02): telemetry models + TraceStore SQLite + TS types (Wave 1)

Task 2-1-01: TelemetryEvent (SQLModel table, composite PK learner/task/seq) + TraceSpan
derived view; SQLAlchemy @validates enforcement (sqlmodel drops Field constraints on table
models). Task 2-1-02: TraceStore protocol (D-019-mirrored) + SQLiteTraceStore with WAL +
synchronous=NORMAL (a-3); concurrent writer/reader no database-locked; idempotent
dedup-on-retry. Task 2-1-03: TS TelemetryEvent/TraceSpan mirroring Python field-for-field
(snake_case for byte-identical JSON); full typecheck green.

195/195 + typecheck pass; ruff clean.

---ci---
phase: 2
milestone: v0.3
status: execute
requirements: {covered: [REQ-3-003], partial: []}
---/ci---

packages/types/index.ts

@@ -1,4 +1,5 @@
 export * from './domain';
 export * from './marketplace';
+export * from './telemetry';
 export * from './user';
 export * from './ui';

packages/types/telemetry.ts

@@ -0,0 +1,44 @@
+/**
+ * Nextcraft — Telemetry Types
+ *
+ * Learner process telemetry: ordered events emitted from sandbox sessions,
+ * aggregated into trace spans for evidence-of-process analysis.
+ *
+ * Source of truth: the Python models in `apps/ai-service/ai_service/telemetry/models.py`
+ * (`TelemetryEvent` / `TraceSpan`). This file mirrors those models
+ * field-for-field; any schema change must be made in both places.
+ */
+
+export type TelemetryKind =
+  | 'command'
+  | 'file_diff'
+  | 'run_result'
+  | 'test_result'
+  | 'activity'
+  | 'stdin'
+  | 'stdout';
+
+export interface TelemetryEvent {
+  learner_id: string;
+  task_id: string;
+  /** Sequence number within the session (int >= 0). */
+  seq: number;
+  kind: TelemetryKind;
+  payload: Record<string, unknown>;
+  /** ISO 8601 datetime string. */
+  ts: string;
+  sandbox_id: string;
+}
+
+/**
+ * Derived view: the ordered event trace for one (learner_id, task_id).
+ * Materialized by the store from persisted TelemetryEvents — mirrors the
+ * Python `TraceSpan` (ai_service/telemetry/models.py), which holds an ordered
+ * `events` sequence. NOT a table on either side.
+ */
+export interface TraceSpan {
+  learner_id: string;
+  task_id: string;
+  /** Ordered events for the (learner, task) pair, sorted by seq. */
+  events: TelemetryEvent[];
+}