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/treemap.md

@@ -0,0 +1,66 @@
+<!-- Source: https://github.com/borealBytes/opencode | License: Apache-2.0 | Author: Clayton Young / Superior Byte Works, LLC (Boreal Bytes) -->
+
+# Treemap Diagram
+
+> **Back to [Style Guide](../mermaid_style_guide.md)** — Read the style guide first for emoji, color, and accessibility rules.
+
+**Syntax keyword:** `treemap-beta`
+**Mermaid version:** v11.12.0+
+**Best for:** Hierarchical data proportions, budget breakdowns, disk usage, portfolio composition
+**When NOT to use:** Simple flat proportions (use [Pie](pie.md)), flow-based hierarchy (use [Sankey](sankey.md))
+
+> ⚠️ **Accessibility:** Treemap diagrams do **not** support `accTitle`/`accDescr`. Always place a descriptive _italic_ Markdown paragraph directly above the code block.
+>
+> ⚠️ **GitHub support:** Treemap is very new — verify it renders on your target GitHub version before using.
+
+---
+
+## Exemplar Diagram
+
+_Treemap showing annual cloud infrastructure costs broken down by service category and specific service, with rectangle sizes proportional to spend:_
+
+```mermaid
+treemap-beta
+"Compute"
+    "EC2 Instances": 45000
+    "Lambda Functions": 12000
+    "ECS Containers": 8000
+"Storage"
+    "S3 Buckets": 18000
+    "RDS Databases": 15000
+    "DynamoDB": 6000
+"Networking"
+    "CloudFront CDN": 9000
+    "API Gateway": 7000
+"Observability"
+    "CloudWatch": 5000
+    "Datadog": 8000
+```
+
+---
+
+## Tips
+
+- Parent nodes (sections) use quoted text: `"Section Name"`
+- Leaf nodes add a value: `"Leaf Name": 123`
+- Hierarchy is created by **indentation** (spaces or tabs)
+- Values determine the size of each rectangle — larger value = larger area
+- Keep to **2–3 levels** of nesting for clarity
+- Use `classDef` and `:::class` syntax for styling nodes
+- **Always** pair with a Markdown text description above for screen readers
+
+---
+
+## Template
+
+_Description of the hierarchical data and what the proportions represent:_
+
+```mermaid
+treemap-beta
+"Category A"
+    "Sub A1": 40
+    "Sub A2": 25
+"Category B"
+    "Sub B1": 20
+    "Sub B2": 15
+```