v0.2.0: Project sync into sandboxes, background processes, and opencode auth login

[cooleel]

New features added:

• Project sync into sandbox
  • Git repos: worktree pushed to a TensorLake-hosted repo and cloned inside the sandbox, with credentials set up so the agent can push changes back.
  • Plain folders: uploaded to a cloud volume and mounted (writes persist durably); skips node_modules and other build junk.
  • Mode auto-detected, overridable via TENSORLAKE_SYNC_MODE=git|volume|off.
  • bash/ls/glob/grep now default to the synced project directory, and the system prompt tells the model where the project lives.
• Migration to the new Tensorlake SDK API
  Moved off the deprecated SandboxClient to the Sandbox.create()/Sandbox.connect() statics.
• Real background processes in the bash tool
  • background=true now uses sandbox.startProcess() and returns a real pid instead of fire-and-forget.
  • New bash_output tool (status + output lines new since last call) and bash_kill tool.
  • Processes stay queryable after exit/kill.
• Reliability hardening
  • Stale sandbox handles (e.g. sandbox resumed on another host) are detected via typed SDK errors, dropped, and idempotent calls retried once — commands never retry, so nothing runs twice.
  • Re-sync is fast-forward-only, so commits made inside the sandbox are never clobbered.
  • Fixed a sandbox stuck mid-suspension being treated as live, and a latent deadlock in the cached-terminated path.
  • Project re-sync no longer blocks the first tool call when the sandbox already has a project copy — refresh runs in the background.
  • bash_output replay after a plugin restart is capped at 200 lines with stale-pid cleanup.
• OpenCode-native auth
  • TensorLake registers as a provider in opencode auth login — no more mandatory env var.
  • Only project-scoped keys (tl_apiKey_…) accepted; the key is validated against the management API before OpenCode stores it in its standard auth.json, and its org/project scope comes from introspection so users never enter IDs separately.
  • Credentials resolved lazily on every use, so logging in mid-session works without restarting OpenCode.
  • TENSORLAKE_API_KEY still works and takes precedence (CI use case); missing credentials now produce an actionable error in chat, a toast, and a log line.
• Housekeeping
  Dependency pins loosened to caret ranges (tensorlake ^0.5.109, @opencode-ai/plugin ^1.18.18), and the README updated throughout (login flow, testing guide, troubleshooting).