feat: add session correlation fields to BoundaryLog proto (#24809)

1 of 9 [next >>](https://github.com/coder/coder/pull/24811)

RFC: [Bridge ↔ Boundaries Correlation
RFC](https://www.notion.so/Bridge-Boundaries-Correlation-313d579be59281f3b4efdbfd6896775a)

Adds three new proto fields for boundary session correlation.

**`ReportBoundaryLogsRequest`**
- `session_id` (string, field 2) — UUID generated by boundary at
startup,
  shared across all batches from a single run.
- `confined_process` (string, field 3) — name of the confined process
  (e.g. `claude-code`, `codex`, `copilot`).

**`BoundaryLog`**
- `sequence_number` (uint64, field 4) — monotonically increasing counter
  per session, primary ordering key when boundary is in use.

`BoundaryLog.time` already existed at field 2; no change needed there.

API version bumped to v2.9.

No behaviour change in coderd or the agent. This is a pure schema bump
that the boundary repo will consume in its own stack.

> Generated by Coder Agents

coderd/workspaceagents_test.go

@@ -3139,7 +3139,7 @@ func requireGetManifest(ctx context.Context, t testing.TB, aAPI agentproto.DRPCA
 }
 
 func postStartup(ctx context.Context, t testing.TB, client agent.Client, startup *agentproto.Startup) error {
-	aAPI, _, err := client.ConnectRPC28(ctx)
+	aAPI, _, err := client.ConnectRPC29(ctx)
 	require.NoError(t, err)
 	defer func() {
 		cErr := aAPI.DRPCConn().Close()