feat(miner-packaging): add laptop-mode CLI entry (SQLite, no Docker, npm install-and-run)

[JSONbored]

Wire the slim "laptop mode" form factor into the gittensory-miner CLI scaffolded in the prior packaging issue: a zero-infra path where npm install -g @jsonbored/gittensory-miner && gittensory-miner init sets up a local SQLite state file and config directory with no Docker/Redis/Postgres dependency, mirroring how packages/gittensory-mcp/bin/gittensory-mcp.js resolves its config path (GITTENSORY_CONFIG_DIR/XDG_CONFIG_HOME fallback chain) and cache directory. This issue is packaging/CLI plumbing only — it does not implement discovery/planning/create logic (those are separate, earlier-phase concerns); it just proves the laptop-mode install-and-run loop boots, creates its state dir, and exits cleanly.

Deliverables

• gittensory-miner init command: creates ~/.config/gittensory-miner/ (respecting GITTENSORY_MINER_CONFIG_DIR/XDG_CONFIG_HOME, same fallback chain as the mcp package's configPath resolution) and an empty SQLite state file inside it.
• gittensory-miner doctor command: reports Node version, config dir path, SQLite file existence/writability, and whether Docker is present (informational only — never required).
• No Docker, Redis, or Postgres import anywhere in this code path — laptop mode must run with zero external services.
• Unit tests covering: fresh init creates the dir/file; re-running init is idempotent (does not clobber existing state); doctor reports absent-Docker gracefully.
• README section documenting the laptop-mode quickstart (npm install -g ... -> init -> doctor).

References

• packages/gittensory-mcp/bin/gittensory-mcp.js lines ~135-141 — the configPath/cacheDir resolution chain to mirror (env var -> XDG -> homedir fallback).
• Prior issue: packages/gittensory-miner/ package skeleton (this extends it).
• New path: packages/gittensory-miner/lib/laptop-init.js (proposed).

[linear-code]

JSO-2426