Add Infrastructure Planning Policy, Database Guidelines, and Terraform Style Guide

[sn0wm1ku]

Requirement

OSBR has no written infrastructure planning policy, so every project starts its
infra decisions from scratch. This adds a policy plus supporting guidelines that
capture OSBR's infrastructure defaults and how we make the recurring decisions,
grounded in big-tech decision frameworks (AWS / Azure / Google Well-Architected,
Google SRE, DORA, The Twelve-Factor App, OWASP / CIS / NIST) right-sized for an
SME.

New pages:

• doc/infra-planning-policy.md (Policies) — 12 guiding principles: scale to
  zero, Zero Trust, IaC mandatory, one-tool-owns-each-resource, reliability &
  delivery measured (SRE/DORA), observability, environments & promotion, backups
  & DR, secrets & least-privilege, deploy safely & reversibly, cost as a design
  constraint, managed-over-self-hosted & data residency — plus grouped references.
• doc/database-guidelines.md (Guideline) — choosing a data store (SQL vs
  NoSQL) and structuring relational schemas, including OSBR's SQL house style
  (strict lowercase snake_case, singular entity / plural table, short
  identifiers driven by a simple ubiquitous language).
• doc/style-guide-terraform.md (Guideline → Style Guide) — Terraform /
  OpenTofu coding conventions (formatting, naming, structure, version pinning,
  remote state, secrets, resource ownership).
• doc/.vitepress/config.mts — sidebar entries for the three pages.

Notes

Related Issues

1. (none)

Implementation is on branch worktree-infra-planning-policy; a draft PR will
follow.

[sn0wm1ku]

Acknowledged. Implementation is already in flight on PR #89 (branch i88-20260713-1954), which covers the three new pages (doc/infra-planning-policy.md, doc/database-guidelines.md, doc/style-guide-terraform.md) plus the sidebar entries in doc/.vitepress/config.mts. Tracking there; this issue can close when #89 merges.

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_{🤖 auto-posted by sn0wm1ku/ghDuty · co-authored by Claude (claude-opus-4-8)}