docs: move Data Engineering to top of nav, fix faint section headers (#29)

As a data engineering tool, the Data Engineering section (agent modes,
tools, guides) should be the first thing users see after Getting Started —
not buried below Configure.

New nav order: Getting Started → Data Engineering → Usage → Configure →
Develop → Reference. This matches the user journey: install, use the data
tools, learn the interfaces, then customize.

Also adds custom CSS to make nav section headers (DATA ENGINEERING, USAGE,
CONFIGURE, etc.) bold uppercase with full contrast instead of the default
faint light-gray styling from the white primary theme.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: anandgupta42

docs/docs/assets/css/extra.css

@@ -0,0 +1,9 @@
+/* Make nav section headers more prominent */
+.md-nav--primary > .md-nav__list > .md-nav__item--section > .md-nav__link {
+  font-weight: 700;
+  color: var(--md-default-fg-color);
+  text-transform: uppercase;
+  font-size: 0.65rem;
+  letter-spacing: 0.05em;
+  opacity: 1;
+}

docs/mkdocs.yml

@@ -35,6 +35,9 @@ theme:
     - search.highlight
     - content.code.copy
 
+extra_css:
+  - assets/css/extra.css
+
 markdown_extensions:
   - admonition
   - pymdownx.details
@@ -47,6 +50,22 @@ markdown_extensions:
 nav:
   - Home: index.md
   - Getting Started: getting-started.md
+  - Data Engineering:
+      - Agent Modes: data-engineering/agent-modes.md
+      - Tools:
+          - Overview: data-engineering/tools/index.md
+          - SQL Tools: data-engineering/tools/sql-tools.md
+          - Schema Tools: data-engineering/tools/schema-tools.md
+          - FinOps Tools: data-engineering/tools/finops-tools.md
+          - Lineage Tools: data-engineering/tools/lineage-tools.md
+          - dbt Tools: data-engineering/tools/dbt-tools.md
+          - Warehouse Tools: data-engineering/tools/warehouse-tools.md
+      - Guides:
+          - Overview: data-engineering/guides/index.md
+          - Cost Optimization: data-engineering/guides/cost-optimization.md
+          - Migration: data-engineering/guides/migration.md
+          - Using with Claude Code: data-engineering/guides/using-with-claude-code.md
+          - Using with Codex: data-engineering/guides/using-with-codex.md
   - Usage:
       - TUI: usage/tui.md
       - CLI: usage/cli.md
@@ -76,22 +95,6 @@ nav:
           - LSP Servers: configure/lsp.md
           - MCP Servers: configure/mcp-servers.md
           - ACP Support: configure/acp.md
-  - Data Engineering:
-      - Agent Modes: data-engineering/agent-modes.md
-      - Tools:
-          - Overview: data-engineering/tools/index.md
-          - SQL Tools: data-engineering/tools/sql-tools.md
-          - Schema Tools: data-engineering/tools/schema-tools.md
-          - FinOps Tools: data-engineering/tools/finops-tools.md
-          - Lineage Tools: data-engineering/tools/lineage-tools.md
-          - dbt Tools: data-engineering/tools/dbt-tools.md
-          - Warehouse Tools: data-engineering/tools/warehouse-tools.md
-      - Guides:
-          - Overview: data-engineering/guides/index.md
-          - Cost Optimization: data-engineering/guides/cost-optimization.md
-          - Migration: data-engineering/guides/migration.md
-          - Using with Claude Code: data-engineering/guides/using-with-claude-code.md
-          - Using with Codex: data-engineering/guides/using-with-codex.md
   - Develop:
       - SDK: develop/sdk.md
       - Server: develop/server.md