[Feature]: Optimize Devin support for Orca dispatch and agent lifecycle (orchestration, accounts, and session telemetry)

### Problem or use case

Orca provides robust multi-agent orchestration for CLI agents like Claude Code and Codex (via `orca dispatch`, worktree isolation, status checking, and handoffs). However, when delegating tasks to Devin, the integration lacks first-class optimization across the agent lifecycle.

In multi-agent workflows (e.g., a lead agent dispatching autonomous workers into isolated worktrees), Devin cannot yet be cleanly dispatched, steered, and monitored with the same reliability as other supported agents. Furthermore, surrounding capabilities like account management and transcript/usage tracking remain fragmented.

### Proposed solution

We propose comprehensive optimization for Devin across Orca's lifecycle, with `orca dispatch` as the primary focus:

1. **Core / Priority: First-class `orca dispatch` orchestration for Devin**
- **Worktree Delegation:** Seamlessly spawn Devin in dedicated worktrees with task contexts, acceptance criteria, and constraints.
- **State & Completion Detection:** Accurately detect Devin's lifecycle states (`running`, `waiting_for_input`, `completed`, `errored`) so that orchestration commands like `orca check --wait` work reliably without brittle sleep loops or terminal scraping.
- **Handoff:** Enable structured context passing and handoffs between Devin and other agents (e.g., Claude Code, Codex, Antigravity).

2. **Account Management & Rate Limiting (`Stats & Usage`)**
- Support `orca account add --agent devin` for credential and profile management (aligning with #18561).
- Integrate Devin usage/quota monitoring into the Stats & Usage view (aligning with #20399).

3. **Session Telemetry, Hooks, and AI Vault Integration**
- Ensure reliable capture and parsing of Devin transcripts in AI Vault.
- Emit standard agent hooks (`orca-status.json` / events) so Devin's real-time progress is visible in the Orca UI and mobile relay.

### Alternatives or additional context

Currently, running Devin within an Orca-managed worktree requires manual terminal invocation and ad-hoc monitoring, bypassing Orca's structured dispatch, automated checks, and unified telemetry.

Providing first-class dispatch and lifecycle support for Devin will enable seamless multi-agent collaboration where Devin acts as a fully-integrated specialist worker alongside Claude Code, Codex, and others.

Start by tracing the existing `orca dispatch` and `orca check --wait` entry points, then compare agent lifecycle handling with the requested Devin states. Done means Devin supports worktree dispatch, handoffs, `orca account add --agent devin`, usage integration, transcript capture, and standard `orca-status.json`/event hooks for the UI and mobile relay.

Written by the indexing model from the issue text.