feat: Enterprise DSS architecture implementation

Complete implementation of enterprise design system validation:

Phase 1 - @dss/rules npm package:
- CLI with validate and init commands
- 16 rules across 5 categories (colors, spacing, typography, components, a11y)
- dss-ignore support (inline and next-line)
- Break-glass [dss-skip] for emergency merges
- CI workflow templates (Gitea, GitHub, GitLab)

Phase 2 - Metrics dashboard:
- FastAPI metrics API with SQLite storage
- Portfolio-wide metrics aggregation
- Project drill-down with file:line:column violations
- Trend charts and history tracking

Phase 3 - Local analysis cache:
- LocalAnalysisCache for offline-capable validation
- Mode detection (LOCAL/REMOTE/CI)
- Stale cache warnings with recommendations

Phase 4 - Project onboarding:
- dss-init command for project setup
- Creates ds.config.json, .dss/ folder structure
- Updates .gitignore and package.json scripts
- Optional CI workflow setup

Architecture decisions:
- No commit-back: CI uploads to dashboard, not git
- Three-tier: Dashboard (read-only) → CI (authoritative) → Local (advisory)
- Pull-based rules via npm for version control

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

packages/dss-rules/rules/spacing.json

@@ -10,7 +10,7 @@
     {
       "id": "no-arbitrary-spacing",
       "name": "No Arbitrary Spacing Values",
-      "description": "Spacing must use token scale (4px increments), not arbitrary values",
+      "description": "Spacing must use token scale, not arbitrary pixel values",
       "severity": "warning",
       "patterns": {
         "forbidden": [
@@ -24,12 +24,7 @@
           "spacing\\.[a-z0-9]+"
         ]
       },
-      "exceptions": [
-        "0",
-        "0px",
-        "auto",
-        "inherit"
-      ]
+      "exceptions": ["0", "0px", "auto", "inherit"]
     },
     {
       "id": "spacing-scale",
@@ -40,29 +35,10 @@
         "type": "scale-check",
         "allowedValues": [0, 4, 8, 12, 16, 20, 24, 32, 40, 48, 64, 80, 96, 128]
       }
-    },
-    {
-      "id": "consistent-component-spacing",
-      "name": "Component Internal Spacing",
-      "description": "Components should use consistent internal spacing patterns",
-      "severity": "info",
-      "guidelines": [
-        "Use spacing.xs (4px) for tight groupings",
-        "Use spacing.sm (8px) for related elements",
-        "Use spacing.md (16px) for section separation",
-        "Use spacing.lg (24px) for major sections",
-        "Use spacing.xl (32px+) for page-level separation"
-      ]
     }
   ],
   "tokens": {
-    "required": [
-      "spacing.xs",
-      "spacing.sm",
-      "spacing.md",
-      "spacing.lg",
-      "spacing.xl"
-    ],
+    "required": ["spacing.xs", "spacing.sm", "spacing.md", "spacing.lg", "spacing.xl"],
     "scale": {
       "xs": "4px",
       "sm": "8px",