refactor: split storage and MCP boundaries

[davidrobertson]

Summary

• Move persisted-event parsing, raw JSONL access, SQLite schema setup, and row decoding out of storage.ts while keeping the LcmStorage API unchanged.
• Move the MCP tool catalog, dispatch logic, and result shaping out of the stdio transport.
• Add focused coverage for valid, malformed, and structurally invalid persisted events.
• Harden nested assignment redaction found during installed CLI testing, while preserving JSON and shell structure plus benign token metrics.

Why

storage.ts and mcp.ts each owned several independent boundaries. This change separates those responsibilities without changing storage formats, MCP schemas, defaults, messages, or ordering.

Validation

• npm run typecheck
• npm test: 199 passed
• npm run smoke
• 31 focused redaction tests, including nested JSON, escaped quotes, empty values, deep assignment chains, and terminal assignments
• 25,000-assignment regression: about 23 ms in the source test and 0.15 seconds through the installed hook
• Installed cache: 49 hook/redaction tests plus smoke
• Fresh isolated codex exec sessions exercised all 17 LCM tools, then rechecked each concrete regression on the final code
• Manual hook, MCP, and CLI round-trips with isolated storage
• npm pack --dry-run --json

Risk

This is a broad code move across persistence and MCP paths. Replay, migration, concurrency, framing, redaction, and recovery tests cover those paths. The frozen final commit passed code, security, QA, goal, maintainability, and runtime gates.