refactor: extract skills from commands across 8 plugins

Refactored commands to extract reusable skills following the
Commands → Skills separation pattern. Each command is now <50 lines
and references skill files for detailed knowledge.

Plugins refactored:
- claude-config-maintainer: 5 commands → 7 skills
- code-sentinel: 3 commands → 2 skills
- contract-validator: 5 commands → 6 skills
- data-platform: 10 commands → 6 skills
- doc-guardian: 5 commands → 6 skills (replaced nested dir)
- git-flow: 8 commands → 7 skills

Skills contain: workflows, validation rules, conventions,
reference data, tool documentation

Commands now contain: YAML frontmatter, agent assignment,
skills list, brief workflow steps, parameters

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/data-platform/commands/lineage-viz.md

@@ -1,18 +1,13 @@
 # /lineage-viz - Mermaid Lineage Visualization
 
+## Skills to Load
+- skills/lineage-analysis.md
+- skills/mcp-tools-reference.md
+- skills/visual-header.md
+
 ## Visual Output
 
-When executing this command, display the plugin header:
-
-```
-┌──────────────────────────────────────────────────────────────────┐
-│  📊 DATA-PLATFORM · Lineage Visualization                         │
-└──────────────────────────────────────────────────────────────────┘
-```
-
-Then proceed with the visualization.
-
-Generate Mermaid flowchart syntax for dbt model lineage.
+Display header: `DATA-PLATFORM - Lineage Visualization`
 
 ## Usage
 
@@ -22,61 +17,16 @@ Generate Mermaid flowchart syntax for dbt model lineage.
 
 ## Workflow
 
-1. **Get lineage data**:
-   - Use `dbt_lineage` to fetch model dependencies
-   - Capture upstream sources and downstream consumers
-
-2. **Build Mermaid graph**:
-   - Create nodes for each model/source
-   - Style nodes by materialization type
-   - Add directional arrows for dependencies
-
-3. **Output**:
-   - Render Mermaid flowchart syntax
-   - Include copy-paste ready code block
-
-## Output Format
-
-```mermaid
-flowchart LR
-    subgraph Sources
-        raw_customers[(raw_customers)]
-        raw_orders[(raw_orders)]
-    end
-
-    subgraph Staging
-        stg_customers[stg_customers]
-        stg_orders[stg_orders]
-    end
-
-    subgraph Marts
-        dim_customers{{dim_customers}}
-        fct_orders{{fct_orders}}
-    end
-
-    raw_customers --> stg_customers
-    raw_orders --> stg_orders
-    stg_customers --> dim_customers
-    stg_orders --> fct_orders
-    dim_customers --> fct_orders
-```
-
-## Node Styles
-
-| Materialization | Mermaid Shape | Example |
-|-----------------|---------------|---------|
-| source | Cylinder `[( )]` | `raw_data[(raw_data)]` |
-| view | Rectangle `[ ]` | `stg_model[stg_model]` |
-| table | Double braces `{{ }}` | `dim_model{{dim_model}}` |
-| incremental | Hexagon `{{ }}` | `fct_model{{fct_model}}` |
-| ephemeral | Dashed `[/ /]` | `tmp_model[/tmp_model/]` |
+1. **Get lineage data**: Use `dbt_lineage` to fetch model dependencies
+2. **Build Mermaid graph**: Apply node shapes from `skills/lineage-analysis.md`
+3. **Output**: Render copy-paste ready Mermaid flowchart
 
 ## Options
 
 | Flag | Description |
 |------|-------------|
-| `--direction TB` | Top-to-bottom layout (default: LR = left-to-right) |
-| `--depth N` | Limit lineage depth (default: unlimited) |
+| `--direction TB` | Top-to-bottom layout (default: LR) |
+| `--depth N` | Limit lineage depth |
 
 ## Examples
 
@@ -86,52 +36,8 @@ flowchart LR
 /lineage-viz rpt_revenue --depth 2
 ```
 
-## Usage Tips
+## Required MCP Tools
 
-1. **Paste in documentation**: Copy the output directly into README.md or docs
-2. **GitHub/GitLab rendering**: Both platforms render Mermaid natively
-3. **Mermaid Live Editor**: Paste at https://mermaid.live for interactive editing
-
-## Example Output
-
-For `/lineage-viz fct_orders`:
-
-~~~markdown
-```mermaid
-flowchart LR
-    %% Sources
-    raw_customers[(raw_customers)]
-    raw_orders[(raw_orders)]
-    raw_products[(raw_products)]
-
-    %% Staging
-    stg_customers[stg_customers]
-    stg_orders[stg_orders]
-    stg_products[stg_products]
-
-    %% Marts
-    dim_customers{{dim_customers}}
-    dim_products{{dim_products}}
-    fct_orders{{fct_orders}}
-
-    %% Dependencies
-    raw_customers --> stg_customers
-    raw_orders --> stg_orders
-    raw_products --> stg_products
-    stg_customers --> dim_customers
-    stg_products --> dim_products
-    stg_orders --> fct_orders
-    dim_customers --> fct_orders
-    dim_products --> fct_orders
-
-    %% Highlight target model
-    style fct_orders fill:#f96,stroke:#333,stroke-width:2px
-```
-~~~
-
-## Available Tools
-
-Use these MCP tools:
 - `dbt_lineage` - Get model dependencies (REQUIRED)
 - `dbt_ls` - List dbt resources
 - `dbt_docs_generate` - Generate full manifest if needed