refactor(core): replace project copies with worktrees - #42149

Summary

• replace the V2 ProjectCopy and ProjectDirectories domains with a global Worktree service
• consolidate project roots and managed worktrees into a dedicated worktree table
• expose global list, create, remove, and refresh operations through the generated Promise and Effect clients
• migrate the current V2 TUI and SDK Next surfaces to Worktree terminology and contracts

Architecture

• keep Worktree service process-global and project-ID based
• keep only the automatic refresh boot node Location-scoped
• resolve create sources from any available persisted worktree, including another managed worktree
• keep Git strategy construction in worktree/git.ts and shared canonical directory validation in worktree/directory.ts
• preserve V2 project resolution, Mercurial support, Bus projection, and durable session adoption behavior

Storage

• add the worktree table for project roots and managed worktrees
• copy every legacy project_directory row without deleting the old table
• convert legacy git_worktree type and strategy values to the git strategy
• retain the deprecated ProjectDirectoryTable definition for compatibility

API

• add global GET, POST, and DELETE /api/experimental/project/:projectID/worktree
• add POST /api/experimental/project/:projectID/worktree/refresh
• remove Location query requirements and the old project directories endpoint
• generate client.worktree.list/create/remove/refresh for Promise and Effect clients

Verification

• Core typecheck and 77 focused project, session, worktree, schema-identity, and migration tests
• Schema typecheck and public event-manifest tests
• Protocol typecheck and generated OpenAPI check
• Client typecheck and 22 Promise contract tests
• Server typecheck and live Worktree HTTP integration test
• CLI typecheck
• TUI typecheck
• SDK Next typecheck and contract identity tests
• no changes under packages/opencode