Onboarding 1.0: folder workspaces + extension scopes (#15)

* docs: add onboarding 1.0 workspace PRD

* feat: add folder workspaces onboarding

* chore: allow custom release notes in workflow dispatch

* feat(onboarding): seed workspace templates, roots UI, and welcome session

.opencode/skill/prd-conventions/SKILL.md

@@ -0,0 +1,43 @@
+---
+name: prd-conventions
+description: PRD authoring conventions for OpenWork
+---
+
+## Rule (Always Use This)
+
+All new PRDs for OpenWork must live at:
+
+- `apps/openwork/pr/<prd-name>.md`
+
+Examples:
+
+- `apps/openwork/pr/onboarding-1.0.md`
+- `apps/openwork/pr/folder-workspaces-jit.md`
+
+## Why
+
+- Keeps PRDs discoverable and consistently named.
+- Avoids bloating `design-prd.md` with long, evolving drafts.
+- Makes it easy to link a PR/branch to a single PRD doc.
+
+## PRD Template (Recommended)
+
+Use this structure:
+
+- Summary
+- Goals / Non-goals
+- Definitions
+- Guiding principles
+- Current state / problem
+- Proposal
+- UX / flows
+- Data / storage
+- Migration
+- Acceptance criteria
+- Open questions
+
+## Naming
+
+- Prefer kebab-case.
+- Include version when appropriate (e.g. `onboarding-1.0`).
+- Keep names stable once a PR is opened.