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/timeline.md

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+<!-- Source: https://github.com/borealBytes/opencode | License: Apache-2.0 | Author: Clayton Young / Superior Byte Works, LLC (Boreal Bytes) -->
+
+# Timeline
+
+> **Back to [Style Guide](../mermaid_style_guide.md)** — Read the style guide first for emoji, color, and accessibility rules.
+
+**Syntax keyword:** `timeline`
+**Best for:** Chronological events, historical progression, milestones over time, release history
+**When NOT to use:** Task durations/dependencies (use [Gantt](gantt.md)), detailed project plans (use [Gantt](gantt.md))
+
+> ⚠️ **Accessibility:** Timelines do **not** support `accTitle`/`accDescr`. Always place a descriptive _italic_ Markdown paragraph directly above the code block.
+
+---
+
+## Exemplar Diagram
+
+_Timeline of a startup's growth milestones from founding through Series A, organized by year and quarter:_
+
+```mermaid
+timeline
+    title 🚀 Startup Growth Milestones
+    section 2024
+        Q1 : 💡 Founded : Built MVP
+        Q2 : 🧪 Beta launch : 100 users
+        Q3 : 📈 Product-market fit : 1K users
+        Q4 : 💰 Seed round : $2M raised
+    section 2025
+        Q1 : 👥 Team of 10 : Hired engineering lead
+        Q2 : 🌐 Public launch : 10K users
+        Q3 : 🏢 Enterprise tier : First B2B deal
+        Q4 : 📊 $1M ARR : Series A prep
+    section 2026
+        Q1 : 🚀 Series A : $15M raised
+```
+
+---
+
+## Tips
+
+- Use `section` to group by year, quarter, or phase
+- Each entry can have multiple items separated by `:`
+- Keep items concise — 2–4 words each
+- Emoji at the start of key items for visual anchoring
+- **Always** pair with a Markdown text description above for screen readers
+
+---
+
+## Template
+
+_Description of the timeline and the period it covers:_
+
+```mermaid
+timeline
+    title 📋 Your Timeline Title
+    section Period 1
+        Event A : Detail one : Detail two
+        Event B : Detail three
+    section Period 2
+        Event C : Detail four
+        Event D : Detail five : Detail six
+```
+
+---
+
+## Complex Example
+
+_Multi-year technology platform evolution tracking a startup's journey from monolith through microservices to AI-powered platform. Six sections span 2020-2025, each capturing key technical milestones and business metrics that drove architecture decisions:_
+
+```mermaid
+timeline
+    title 🚀 Platform Architecture Evolution
+    section 2020 — Monolith Era
+        Q1 : 💡 Founded company : Rails monolith launched : 10 engineers
+        Q3 : ⚠️ Hit scaling ceiling : 50K concurrent users : Database bottleneck
+    section 2021 — Breaking Apart
+        Q1 : 🔐 Extracted auth service : 🐳 Adopted Docker : CI/CD pipeline live
+        Q3 : 📦 Split order processing : ⚡ Added Redis cache : 200K users
+    section 2022 — Microservices
+        Q1 : ⚙️ 8 services in production : ☸️ Kubernetes migration : Service mesh pilot
+        Q3 : 📥 Event-driven architecture : 📊 Observability stack : 500K users
+    section 2023 — Platform Maturity
+        Q1 : 🌐 Multi-region deployment : 🛡️ Zero-trust networking : 50 engineers
+        Q3 : 🔄 Canary deployments : 📈 99.99% uptime SLA : 2M users
+    section 2024 — AI Integration
+        Q1 : 🧠 ML recommendation engine : ⚡ Real-time personalization
+        Q3 : 🔍 AI-powered search : 📊 Predictive analytics : 5M users
+    section 2025 — Next Generation
+        Q1 : ☁️ Edge computing rollout : 🤖 AI agent platform : 10M users
+```
+
+### Why this works
+
+- **6 sections are eras, not just years** — "Monolith Era", "Breaking Apart", "Microservices" tell the story of _why_ the architecture changed, not just _when_
+- **Business metrics alongside tech milestones** — user counts and team size appear next to architecture decisions. This shows the _pressure_ that drove each evolution (50K users → scaling ceiling → extracted services)
+- **Multiple items per time point** — each quarter packs 2-3 items separated by `:`, giving a dense but scannable view of everything happening in parallel
+- **Emoji anchors the scan** — eyes land on 🧠 ML, 🌐 Multi-region, ⚡ Redis before reading the text. For a quick skim, the emoji alone tells the story