Add current worktree shortcuts to Orca CLI

[Jinwoo-H]

Problem

Agents working inside an Orca-managed worktree had no first-class CLI affordance for identifying or targeting the current worktree. Users had to spell out selectors like path:$PWD, and the help/docs/agent skill text did not advertise a self-aware workflow.

Solution

Add orca worktree current and support active / current as CLI-level worktree selector shortcuts that resolve from the caller's current directory into a path: selector before crossing the runtime boundary. Update CLI help, focused-v1/spec docs, and the Orca CLI skill docs, and add tests covering the new selector normalization plus the runtime boundary behavior.

Verification

• pnpm exec vitest run src/cli/index.test.ts src/main/runtime/orca-runtime.test.ts
• pnpm run typecheck:cli
• pnpm run build:cli
• node out/cli/index.js --help
• node out/cli/index.js worktree current --help
• node out/cli/index.js worktree set --help