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/mindmap.md

@@ -0,0 +1,74 @@
+<!-- Source: https://github.com/borealBytes/opencode | License: Apache-2.0 | Author: Clayton Young / Superior Byte Works, LLC (Boreal Bytes) -->
+
+# Mindmap
+
+> **Back to [Style Guide](../mermaid_style_guide.md)** — Read the style guide first for emoji, color, and accessibility rules.
+
+**Syntax keyword:** `mindmap`
+**Best for:** Brainstorming, concept organization, knowledge hierarchies, topic breakdown
+**When NOT to use:** Sequential processes (use [Flowchart](flowchart.md)), timelines (use [Timeline](timeline.md))
+
+> ⚠️ **Accessibility:** Mindmaps do **not** support `accTitle`/`accDescr`. Always place a descriptive _italic_ Markdown paragraph directly above the code block.
+
+---
+
+## Exemplar Diagram
+
+_Mindmap showing a platform engineering team's key responsibility areas organized into infrastructure, developer experience, security, and observability domains:_
+
+```mermaid
+mindmap
+    root((🏗️ Platform Engineering))
+        ☁️ Infrastructure
+            Kubernetes clusters
+            Service mesh
+            Load balancing
+            Auto-scaling
+        🔧 Developer Experience
+            CI/CD pipelines
+            Local dev environments
+            Internal CLI tools
+            Documentation
+        🔐 Security
+            Secret management
+            Network policies
+            Vulnerability scanning
+            Access control
+        📊 Observability
+            Metrics collection
+            Log aggregation
+            Distributed tracing
+            Alerting rules
+```
+
+---
+
+## Tips
+
+- Keep to **3–4 main branches** with **3–5 sub-items** each
+- Use emoji on branch headers for visual distinction
+- Don't nest deeper than 3 levels
+- Root node uses `(( ))` for circle shape
+- **Always** pair with a Markdown text description above for screen readers
+
+---
+
+## Template
+
+_Description of what this mindmap shows and the key categories it covers:_
+
+```mermaid
+mindmap
+    root((🎯 Central Concept))
+        📋 Branch One
+            Sub-item A
+            Sub-item B
+            Sub-item C
+        🔧 Branch Two
+            Sub-item D
+            Sub-item E
+        📊 Branch Three
+            Sub-item F
+            Sub-item G
+            Sub-item H
+```