feat: optional game system per item; Markdown copy grouped system → lot → items (0.4.0)

[mabry1985]

Game system + grouped Markdown copy

An optional system on every item (Warhammer 40K, Blood Bowl, …). The grid orders and filters by it; the item dialog and inline edit offer the systems already in use. Copy as Markdown becomes a document:

## Blood Bowl
### Blood Bowl Collection
- Reikland Reavers Human Team — Blood Bowl 2016 Split — $57.69

## Warhammer 40K
### Armageddon Box
- Warboss — Orks — $16.00

Also closes Vera's finding on #5: the copy re-reads the live list so a row deleted elsewhere cannot leak into the text.

The column arrives via the store's additive migration; an existing database is upgraded on open (test included). 128 tests; smoke-tested in the local harness.

🤖 Generated with Claude Code

https://claude.ai/code/session_011UQ33xXfygwEkzbbJx3YwZ

[protoreview]

QA panel review — WARN

code-review-structural · head 74e6daa98241 · formal

⚠️ PR advanced 1 commit(s) during this round (74e6daa98241 → 8eb242e81695); 0 finding(s) in the delta were demoted to possibly addressed.

Low-risk PR: adds a /systems GET endpoint to the inventory API. The code change itself is clean; the single finding is a documentation gap — the README's API listing was not updated to reflect the new route. Fix first: add systems to the README's API line. The panel did not disagree on anything (single finding, confirmed by the verifier). Verification confirmed the evidence quote matches the file byte-for-byte at line 19. Coverage gap: the structural pass was skipped, and api.py itself received no findings — the panel's attention went to the README omission, so the endpoint's implementation logic went under-read.

Findings

	Severity	Location	Finding	Verified
🟡	minor	README.md:19	The README's API endpoint listing does not include the new /systems GET endpoint added in api.py, so the documented API surface is incomplete relative to the…	confirmed

findings JSON (machine-readable)

[
  {
    "file": "README.md",
    "line": 19,
    "severity": "minor",
    "category": "conventions",
    "claim": "The README's API endpoint listing does not include the new `/systems` GET endpoint added in api.py, so the documented API surface is incomplete relative to the code.",
    "evidence": "| **API** | bearer-gated JSON under `/api/plugins/inventory` \u2014 `summary`, `lots`, `items`, `items/{id}/price`, `items/{id}/sold`, `items/{id}/listings`, `listings/{id}/end`, `sales`, `stale`, `audit`, `import`, `export` |",
    "verdict": "confirmed",
    "note": "The /systems route is added in api.py (visible in diff) but the README's API line (unchanged by the PR) omits it; evidence quote matches the file verbatim at line 19."
  }
]