Fix unresolved placeholders in start and review-agent skills for trunk-based workflows

[sebastientaggart]

When a project uses trunk-based workflow (BRANCH_DEV not configured) or leaves PLATFORM_COMPLIANCE_NOTES / CONVENTIONS_NOTES undefined, sync.sh warns about unresolved placeholders in the generated skill files. This affects any project that uses the default template configuration, since those keys are commented out by default. The fix is to wrap these placeholder references in conditional blocks so they are only included when the corresponding config values are defined.

[sebastientaggart]

Agent Implementation Notes

Bug 1 — BRANCH_DEV in skills/start.md

Lines 164-167 (Case A Step 4) and 224-227 (Case B Step 3) reference {{BRANCH_DEV}} outside any conditional block:

git checkout {{BRANCH_DEV}} && git pull origin {{BRANCH_DEV}}
(In trunk mode where `{{BRANCH_DEV}}` is empty, use `{{BRANCH_PROD}}` instead.)

Fix: wrap each occurrence in {{#if BRANCH_DEV}} / {{#if !BRANCH_DEV}} conditionals. When BRANCH_DEV is set, show the dev branch command. When not set, show the prod branch command directly (no 'trunk mode' note needed since that IS the mode).

Bug 2 — PLATFORM_COMPLIANCE_NOTES and CONVENTIONS_NOTES in skills/review-agent.md

Lines 54 and 67 reference these placeholders unconditionally. The default template has them commented out.

Fix: wrap each in {{#if}} conditionals. When not defined, omit the placeholder entirely (the HTML comment above already explains what to do).

Files to change:

• skills/start.md — 2 locations (Case A Step 4, Case B Step 3)
• skills/review-agent.md — 2 locations (PLATFORM_COMPLIANCE_NOTES, CONVENTIONS_NOTES)