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-history.table.golden

@@ -0,0 +1,14 @@
+exit: 0
+--- stdout
+History for BBCA.JK
+┌────────────┬───────┬───────┬───────┬───────┬────────────┐
+│ DATE       ┆ OPEN  ┆ HIGH  ┆ LOW   ┆ CLOSE ┆ VOLUME     │
+╞════════════╪═══════╪═══════╪═══════╪═══════╪════════════╡
+│ 2024-03-01 ┆ 9,800 ┆ 9,900 ┆ 9,750 ┆ 9,875 ┆ 12,300,000 │
+├╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
+│ 2024-03-02 ┆ 9,850 ┆ 9,920 ┆ 9,800 ┆ 9,880 ┆ 11,000,000 │
+├╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
+│ 2024-03-03 ┆ 9,860 ┆ 9,950 ┆ 9,820 ┆ 9,925 ┆ 14,000,000 │
+└────────────┴───────┴───────┴───────┴───────┴────────────┘
+--- stderr
+info: history provider fallback active (msn -> yahoo)