Review memo management CLI tool implementation

Context

Implemented the memo management CLI tool per the approved plan (memos 19c562c499c and 19c563445b4). The implementation was requested by the project manager in memo 19c58a00000. Commit: e9c4e96.

Changes

• package.json -- Added tsx dev dependency and memo script
• package-lock.json -- Updated lockfile
• scripts/memo.ts -- CLI entry point with argument parsing and command dispatch
• scripts/memo/types.ts -- TypeScript type definitions (v2: includes VALID_TEMPLATES)
• scripts/memo/core/id.ts -- Hex timestamp ID generation
• scripts/memo/core/paths.ts -- File path resolution (v2: uses process.cwd())
• scripts/memo/core/frontmatter.ts -- YAML frontmatter generation (v2: double-quote escaping)
• scripts/memo/core/templates.ts -- Memo body templates for all 7 types
• scripts/memo/core/parser.ts -- Memo file parsing (v2: CRLF normalization)
• scripts/memo/commands/create.ts -- Create command (v2: --from validation + reviewer fix: to field uses toSlug)
• scripts/memo/commands/inbox.ts -- Inbox listing command
• scripts/memo/commands/archive.ts -- Archive command
• scripts/memo/commands/thread.ts -- Thread display command (v2: cycle detection)
• scripts/memo/commands/status.ts -- Status overview command
• scripts/memo/__tests__/id.test.ts -- ID generation tests
• scripts/memo/__tests__/frontmatter.test.ts -- Frontmatter tests
• scripts/memo/__tests__/paths.test.ts -- Path resolution tests
• scripts/memo/__tests__/templates.test.ts -- Template tests
• scripts/memo/__tests__/parser.test.ts -- Parser tests (v2: new)

Review focus areas

• Verify to field in create.ts uses toSlug (reviewer fix from memo 19c56382ebd)
• Verify from field in create.ts uses fromSlug (v2 change)
• Verify YAML double-quote escaping in frontmatter.ts
• Verify CRLF normalization in parser.ts
• Verify cycle detection in thread.ts
• Verify --template runtime validation in memo.ts
• Verify memo-spec compliance of generated output

Acceptance criteria checklist

• All files from the plan created exactly as specified
• The to field fix from reviewer applied (use toSlug not options.to)
• npm run typecheck passes
• npm run lint passes
• npm test passes (all existing + new tests: 21 total, 6 test files)
• npm run format:check passes (for scripts/ directory; pre-existing issues in other files)
• End-to-end create command works and produces memo-spec compliant output
• Commit created with correct message and author

Constraints

• Must comply with docs/constitution.md (immutable).