docs: roadmap, CLI config schema, and rules-engine spec (#40)

## What

Adds the strategic + contract docs for the next phase. **Docs/config
only — no source changes.**

- **`roadmap.md`** — phased roadmap in two tracks: *parity* (dead code,
duplication, health, boundaries, audit gate, output formats,
suppressions, LSP) and *differentiation*. Flagship: **Highways** —
data-flow convergence that detects divergent "cowpaths" for one logical
data operation and **proposes the canonical unified path** (name,
location, signature, reroute plan). Read-only stance; LSP yes; no
auto-fix / no VS Code extension.
- **`schema.json`** — JSON Schema (draft 2020-12) for the CLI config:
ESLint-style `rules` (incl. `no-comments`), `boundaries`, `thresholds`,
`ci` gate.
- **`codebase-intelligence.json`** — example/default config
(schema-linked, dogfooded).
- **`specs/backlog/2026-06-02-config-rules-engine.md`** — config
discovery + loader, ESLint-style rules engine, `no-comments` rule, and
CI gate (exit codes, formats, GitHub/GitLab).

## Notes
- No competitor referenced anywhere.
- Implementation of the engine is **not** in this PR — spec only.

## Test
Docs/JSON only. `schema.json` + `codebase-intelligence.json` validated
(parse + rule-name alignment).

Author: bntvllnt

codebase-intelligence.json

@@ -0,0 +1,49 @@
+{
+  "$schema": "./schema.json",
+  "root": ".",
+  "include": ["src/**/*.ts"],
+  "exclude": ["src/**/*.test.ts", "tests/**", "dist/**"],
+  "entry": ["src/cli.ts"],
+  "ignore": {
+    "exportsUsedInFile": false
+  },
+  "rules": {
+    "no-circular-deps": "error",
+    "no-dead-exports": "warn",
+    "no-dead-files": "warn",
+    "no-unused-deps": "warn",
+    "no-duplication": ["warn", { "minTokens": 50, "mode": "mild" }],
+    "max-cyclomatic-complexity": ["warn", { "max": 20 }],
+    "no-boundary-violations": "warn",
+    "no-divergent-paths": "off",
+    "no-comments": "off"
+  },
+  "boundaries": {
+    "zones": [
+      { "name": "types", "patterns": ["src/types/**"] },
+      { "name": "parser", "patterns": ["src/parser/**"] },
+      { "name": "graph", "patterns": ["src/graph/**"] },
+      { "name": "analyzer", "patterns": ["src/analyzer/**"] },
+      { "name": "core", "patterns": ["src/core/**"] },
+      { "name": "surfaces", "patterns": ["src/cli.ts", "src/mcp/**"] }
+    ],
+    "rules": [
+      { "from": "types", "forbid": ["parser", "graph", "analyzer", "core", "surfaces"] },
+      { "from": "parser", "allow": ["types"] },
+      { "from": "graph", "allow": ["types", "parser"] },
+      { "from": "analyzer", "allow": ["types", "graph"] }
+    ]
+  },
+  "thresholds": {
+    "health": { "minScore": 80 }
+  },
+  "output": {
+    "format": "text",
+    "quiet": false
+  },
+  "ci": {
+    "gate": "new-only",
+    "failOn": "error",
+    "maxWarnings": -1
+  }
+}