[FEATURE]: Expose V2 project current and directories APIs #34432

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Expose V2 project APIs through packages/protocol, server handlers, and the generated @opencode-ai/client.

From #34359, the TUI currently relies on legacy client calls for:

• project.current
• project.directories

Observed TUI usage on origin/v2:

• packages/tui/src/context/project.tsx loads the current project for the active workspace and then loads project directories to derive project/worktree/main directory state.
• packages/tui/src/component/dialog-move-session.tsx refreshes project copies and lists directories for the move-session / working-copy dialog.

Expected scope:

• Add protocol/server/client surface for current project lookup.
• Add protocol/server/client surface for project directories.
• Preserve workspace/location query semantics needed by the TUI.
• Regenerate @opencode-ai/client.
• Add tests around request/response shape and missing-project behavior.

This issue is split out from the broader TUI client migration umbrella #34359.