Feature: optional branch bootstrap during /dmx/init

[hpieris-dm]

Problem

/dmx/init detects integration and production branches from what already exists in the repo (staging → main → master). When none of those branches exist locally or on the remote, init sets branch_base: {REQUIRED} and downstream skills cannot proceed until the user manually creates and pushes a branch outside the workflow.

This is a common friction point on new or empty repositories where no default branch has been established yet.

Proposal

Add optional branch bootstrap during init — not silent auto-creation of multiple standard branch names.

Suggested approach:

1. Detect empty or branch-less repos — no local branch and/or no recognizable integration branch on the remote.
2. Prompt the user — e.g. "No integration branch found. Create main as the integration branch?" with a sensible default name.
3. Create only what was agreed — single branch, local checkout, optional initial commit if the repo is completely empty; push only when the user confirms and a remote exists.
4. Never overwrite — do not create or rename branches when candidates already exist; do not auto-create master, staging, and development as a bundle.

Out of scope

• Replacing a team's existing branch topology
• Creating protected branches without explicit user consent
• Guessing production vs integration roles when both main and master exist (init already asks in that case)

Acceptance criteria

• Init handles repos with no integration branch without leaving branch_base: {REQUIRED} as the only outcome
• Branch creation is opt-in and user-confirmed
• Existing repos with established branches behave exactly as today
• Config written after bootstrap includes valid branch_base (and production_branch where detectable)

Context

Related skill: dmx-init — branch detection in Step 2 (integration / production role resolution).