feat: implement scanner rules, CLI, tests, and lint config

[dmchaledev]

Summary

Implements the full MCP security scanner library from the ground up.

New files

• src/types.ts — Severity/RuleId enums, Finding/ScanConfig/SecurityReport interfaces
• src/parser.ts — parseConfig() reads JSON/YAML config files and normalises to ParsedMcpConfig
• src/scorer.ts — computeScore() and computeSummary()
• src/rules/auth-rules.ts — NO_AUTH, WEAK_API_KEY, MISSING_TLS rules
• src/rules/injection-rules.ts — TOOL_DESC_INJECTION, UNSAFE_TOOL_OUTPUT_PATH rules
• src/rules/config-rules.ts — WILDCARD_CORS, VERBOSE_ERRORS, OVERPRIVILEGED_TOOL rules
• src/rules/index.ts — Rule interface + getAllRules()
• src/scanner.ts — scan() main entry point
• src/index.ts — public re-exports (replaces stub)
• src/cli.ts — CLI entry point (exit code 1 on failure)
• src/__tests__/scanner.test.ts — 27 integration + unit tests
• src/__tests__/scorer.test.ts — 8 scorer unit tests

Config files

• jest.config.cjs — ts-jest in CJS mode with .js → .ts resolver
• .eslintrc.cjs — ESLint + @typescript-eslint

Results

• ✅ Build: tsc passes with zero errors
• ✅ Tests: 35/35 pass
• ✅ Lint: zero warnings