feat: Add foundational documentation for security, workflow, and project management

- Create SECURITY.md to outline security policies and practices.
- Establish WORKFLOW.md detailing the project lifecycle from planning to retrospective.
- Introduce decision log structure in decisions/README.md for tracking architecture decisions.
- Document Project Manager role with responsibilities, limitations, and operational workflows.
- Implement templates for ADRs, bugs, meetings, projects, retrospectives, RFCs, roadmaps, and sprints.
- Set up memory logs for architecture and company-wide lessons learned.
- Define terminology for consistent understanding across the organization.

templates/SPRINT.md

@@ -0,0 +1,38 @@
+# Sprint <N> — <Project Name>
+
+**Start:** YYYY-MM-DD
+**End:** YYYY-MM-DD
+**Opened by:** Project Manager
+
+## Goal
+
+One or two sentences: what this sprint is meant to accomplish, in terms of the Stories it pulls
+in — not a restatement of the whole Epic.
+
+## Stories in scope
+
+- [ ] Story — link to Plane
+- [ ] Story — link to Plane
+
+Pulled from Stories the CEO has already prioritized (`PLANE.md`) — a sprint should not include
+un-prioritized backlog items.
+
+## Assignments
+
+| Task | Role | Assignee |
+|---|---|---|
+| | | |
+
+## Blockers watch
+
+Anything the Project Manager is actively tracking mid-sprint. Update as they arise/resolve —
+this section should reflect current state, not accumulate history (that belongs in the
+retrospective).
+
+## Close-out
+
+**Closed:** YYYY-MM-DD
+**Completed / carried over:** summary of what finished vs. moved to the next sprint, and why.
+**Velocity note:** link to Plane's burndown view rather than re-deriving numbers here.
+
+Followed by a retrospective — see `templates/RETROSPECTIVE.md`.