fix: telemetry/memory flag mismatches, doc drift; add CI; self-dogfood

Parallel fleet audit (2 background agents) + direct work:

- src/commands/memory.mjs: `memory put --allow-secrets` was read as
  `flags.allowSecrets` (camelCase) but the CLI parser only emits
  kebab-case keys, so the flag was always undefined/false. Fixed to
  `flags['allow-secrets']`.
- Docs: `lh graph --brief` was referenced 14x across 5 agent.md files,
  harness.instructions.md, 4 SKILL.md files, onboard.prompt.md, and
  README, but `lh graph` has no --brief flag (terse output is already
  the default, --json/--severity are the only flags). Corrected every
  reference to match actual CLI surface.
- .github/workflows/ci.yml: run npm install/validate/test on node 20+22.
- Self-dogfooded `lh init --yes` in this repo, producing .agents/
  (harness.config.json, architecture.md, conventions.md, memory
  shards). `lh doctor` now reports all required checks green.
- Deduped .gitignore harness block against init's auto-managed block.

Verified: 53/53 tests pass, validate 0 errors, doctor all-green.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/skills/plan/SKILL.md

@@ -8,7 +8,7 @@ description: Use when decisions are complete and the harness must produce a spec
 1. Read `.agents/specs/<slug>/decisions.md`.
 2. Invoke `.github/agents/architect.agent.md` for `.agents/specs/<slug>/spec.md`.
 3. Invoke `.github/agents/splitter.agent.md` for `.agents/specs/<slug>/plan.dag.json`.
-4. Run `lh graph --brief`.
+4. Run `lh graph`.
 5. Report spec path, DAG path, acceptance ids, and blockers.
 
 Do not build before the DAG passes structural gates.