test: add golden output parity gate and live A/B compare

Phase 0 of docs/DESIGN.md, before any refactor code:

- tests/golden.rs runs every case in tests/golden/cases.toml (126
  outputs across help, completions, config, cache, all stocks commands
  on MSN and Yahoo mocks, error paths, and ownership queries on a seeded
  fixture DB) and compares exit code, stdout, and stderr byte for byte.
  Regenerate only with UPDATE_GOLDEN=1 for a reviewed output change.
- scripts/live-smoke.sh --compare <old-idx> runs each live case with
  both binaries and fails on differing exit codes, added/missing/retyped
  JSON keys, or changed values for slow-moving data.
- Exclude golden files from the whitespace/EOF pre-commit fixers, which
  would otherwise rewrite pinned help output.

Both gates were fault-injected: a one-word table change fails exactly
the three history goldens, and a binary dropping profile.long_name fails
only the profile live comparison.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/golden/stocks-technical.json.golden

@@ -0,0 +1,28 @@
+exit: 0
+--- stdout
+{
+  "symbol": "BBCA.JK",
+  "as_of": "2024-03-03",
+  "current_price": 9925,
+  "sma20": null,
+  "sma50": null,
+  "sma200": null,
+  "rsi14": null,
+  "macd": {
+    "line": null,
+    "signal": null,
+    "histogram": null
+  },
+  "volume": {
+    "current": 14000000,
+    "average20": null,
+    "ratio20": null
+  },
+  "signals": {
+    "rsi": "Neutral",
+    "macd": "Neutral",
+    "trend": "Neutral",
+    "overall": "Neutral"
+  }
+}
+--- stderr