docs(references): port style guides, 24 diagram guides, and 9 templates from opencode

All content ported from borealBytes/opencode under Apache-2.0 license with
attribution headers prepended to each file.

- references/markdown_style_guide.md (~733 lines): full markdown formatting,
  citation, collapsible sections, emoji, Mermaid integration, and template
  selection guide
- references/mermaid_style_guide.md (~458 lines): full Mermaid standards —
  emoji set, classDef color palette, accessibility (accTitle/accDescr),
  theme neutrality (no %%{init}), and diagram type selection table
- references/diagrams/ (24 files): per-type exemplars, tips, and templates
  for all Mermaid diagram types
- templates/ (9 files): PR, issue, kanban, ADR, presentation, how-to,
  status report, research paper, project docs

Source: https://github.com/borealBytes/opencode

scientific-skills/markdown-mermaid-writing/references/diagrams/sankey.md

@@ -0,0 +1,71 @@
+<!-- Source: https://github.com/borealBytes/opencode | License: Apache-2.0 | Author: Clayton Young / Superior Byte Works, LLC (Boreal Bytes) -->
+
+# Sankey Diagram
+
+> **Back to [Style Guide](../mermaid_style_guide.md)** — Read the style guide first for emoji, color, and accessibility rules.
+
+**Syntax keyword:** `sankey-beta`
+**Best for:** Flow magnitude visualization, resource distribution, budget allocation, traffic routing
+**When NOT to use:** Simple proportions (use [Pie](pie.md)), process steps (use [Flowchart](flowchart.md))
+
+> ⚠️ **Accessibility:** Sankey diagrams do **not** support `accTitle`/`accDescr`. Always place a descriptive _italic_ Markdown paragraph directly above the code block.
+
+---
+
+## Exemplar Diagram
+
+_Sankey diagram showing how a $100K monthly cloud budget flows from the total allocation through service categories (compute, storage, networking, observability) to specific AWS services, with band widths proportional to cost:_
+
+```mermaid
+sankey-beta
+
+Cloud Budget,Compute,45000
+Cloud Budget,Storage,25000
+Cloud Budget,Networking,15000
+Cloud Budget,Observability,10000
+Cloud Budget,Security,5000
+
+Compute,EC2 Instances,30000
+Compute,Lambda Functions,10000
+Compute,ECS Containers,5000
+
+Storage,S3 Buckets,15000
+Storage,RDS Databases,10000
+
+Networking,CloudFront CDN,8000
+Networking,API Gateway,7000
+
+Observability,CloudWatch,6000
+Observability,Datadog,4000
+```
+
+---
+
+## Tips
+
+- Format: `Source,Target,Value` — one flow per line
+- Values determine the width of each flow band
+- Keep to **3 levels** maximum (source → category → destination)
+- Blank lines between groups improve source readability
+- Good for answering "where does the 💰 go?" questions
+- No emoji in node names (parser limitation) — use descriptive text
+- **Always** pair with a Markdown text description above for screen readers
+
+---
+
+## Template
+
+_Description of what flows from where to where and what the magnitudes represent:_
+
+```mermaid
+sankey-beta
+
+Source,Category A,500
+Source,Category B,300
+Source,Category C,200
+
+Category A,Destination 1,300
+Category A,Destination 2,200
+
+Category B,Destination 3,300
+```