T3 Code Android v0.2.6

Worktree thread fix.

• New thread now shows a Base branch picker when you choose New worktree.
• The picker loads real local/remote branches from the project checkout and defaults to the repository's default branch (or the current branch).
• Worktree launches now send the required baseRef, which fixes server defect: Missing key at ["workspaceStrategy"]["baseRef"].
• The Start button stays disabled until a base branch is available, with inline loading, error, and retry states.
• Switching projects reloads branches and clears the previous selection.
• Version 0.2.6 (versionCode 8).