Add Daytona sandbox provider plugin (#5580)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Agents need isolated sandbox environments to execute work safely;
Paperclip already supports E2B as a sandbox provider plugin
> - Users want to use Daytona (https://www.daytona.io/) as an
alternative sandbox backend, but no plugin existed for it
> - Without a Daytona plugin, teams that prefer Daytona's
pricing/regions/runtime can't run Paperclip agents on it
> - This pull request adds a `@paperclip/sandbox-provider-daytona`
plugin that mirrors the existing E2B plugin shape and wires up Daytona's
`@daytonaio/sdk` for sandbox lifecycle, command execution, and shell
detection
> - The benefit is that operators can pick Daytona as a first-class
sandbox provider without touching core code, broadening Paperclip's
runtime options

## What Changed

- New plugin package `packages/plugins/sandbox-providers/daytona` with
manifest, worker entry, and provider implementation backed by
`@daytonaio/sdk`
- Implements sandbox create/destroy/exec/upload/download lifecycle,
shell command detection, and config/env wiring consistent with the E2B
plugin
- Adds unit tests under `src/plugin.test.ts` and a README documenting
setup and the `DAYTONA_API_KEY` requirement
- Minor adjustments in `scripts/paperclip-issue-update.sh`,
`packages/shared/src/issue-thread-interactions.test.ts`, and
`packages/shared/src/validators/issue.ts` to support the integration

## Verification

- Re-ran the full sandbox provider matrix on the QA Paperclip instance
using Daytona as the runtime — all 6 adapters executed inside the
Daytona sandbox with zero `environmentExecute` timeouts
- 5/6 adapters pass cleanly (or with informational warns); the only
failure is `codex_local`, which is an OpenAI quota/billing issue
unrelated to Daytona
- `pnpm --filter @paperclip/sandbox-provider-daytona test` runs the
plugin unit tests

## Risks

- New optional plugin; no behavior change for users who don't enable it
- Requires `DAYTONA_API_KEY` for runtime use — documented in the plugin
README
- Daytona SDK is a new external dependency; tracked in the plugin's own
package.json so it doesn't affect the core install footprint

## Model Used

- Claude Opus 4.7 (`claude-opus-4-7`), extended thinking, tool use
enabled

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots (N/A — backend plugin)
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

packages/plugins/sandbox-providers/daytona/src/worker.ts

@@ -0,0 +1,5 @@
+import { runWorker } from "@paperclipai/plugin-sdk";
+import plugin from "./plugin.js";
+
+export default plugin;
+runWorker(plugin, import.meta.url);