feat(sandbox): thread backend.interactions through stream prompt options

[vutuanlinh2k2]

Closes #165.

Summary

The sandbox question channel — where an agent pauses mid-turn to ask the user a clarifying question — is off unless the session's backend.interactions is set. agent-app builds the backend object but hardcoded it to { type, profile, ...model } with no interactions, so consumers like gtm-agent could not enable it. agent-app was the missing link between the published SDK surface (@tangle-network/sandbox@0.9.7) and consumers.

This threads an opt-in interactions passthrough through the streaming/interactive prompt path and deliberately withholds it from the detached path (which has no consumer to answer a question). The field is forwarded verbatim — agent-app does not duplicate the per-harness support matrix; the sidecar rejects unsupported kinds loudly at session init, and a local matrix would drift.

Changes

• package.json — bump @tangle-network/sandbox devDep ^0.9.5→^0.9.7 and raise the peerDependency floor >=0.9.4→>=0.9.7. Older SDKs strip the field client-side (normalizeRuntimeBackendConfig), so the floor makes the requirement explicit.
• StreamSandboxPromptOptions — new inline-typed interactions?: { question?; permission?; plan? } option (no BackendConfig import; typechecks independent of SDK version via the existing cast).
• streamSandboxPrompt — spreads interactions verbatim into the backend, mirroring the model spread.
• driveSandboxTurn — left untouched, with a comment documenting the policy (detached cron/mission-step turns have no consumer to answer a question). Box-create payload also untouched.
• detectInteractiveQuestion — extended to recognize the generic interaction/kind:"question" event shape (the SDK docstring confirms enabled kinds surface exactly as interaction stream events), strengthening the disallowQuestions backstop.
• Tests — verbatim forwarding on the streaming path, undefined by default, driveSandboxTurn never sets it, and the detector recognizing/ignoring interaction events.

Note on the issue's file reference

The issue points at runSandboxPrompt / :1784 as the autonomous path to avoid. In the actual code, runSandboxPrompt builds no backend (it delegates to streamSandboxPrompt); the function at :1784 is driveSandboxTurn, the detached box.prompt path — that is the one left untouched.

Acceptance criteria

• StreamSandboxPromptOptions.interactions exists and reaches box.streamPrompt's backend config verbatim (test)
• Autonomous/non-streaming path (driveSandboxTurn) never sets it (test)
• @tangle-network/sandbox bumped to ≥ 0.9.7
• New agent-app version published for gtm-agent to consume (release flow after merge)

Verification

• pnpm typecheck — clean
• pnpm test src/sandbox/index.test.ts — interaction/sandbox tests pass (6 targeted, 110 total)
• pnpm build — ESM + DTS both succeed

Two pre-existing, environment-specific failures are unrelated to this change: the deferred profile files suite shells out to a real bash that breaks on the local .bash_profile (confirmed failing identically on clean main), and the DTS build needs NODE_OPTIONS=--max-old-space-size=8192 on this machine due to the existing type-surface size.