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/ownership-graph-dot.table.golden

@@ -0,0 +1,20 @@
+exit: 0
+--- stdout
+digraph ownership {
+  rankdir=LR;
+  graph [fontname="Helvetica"];
+  node [fontname="Helvetica"];
+  edge [fontname="Helvetica"];
+
+  "entity:14" [label="DWIMURIA INVESTAMA ANDALAN", shape=ellipse];
+  "entity:15" [label="CATURGUWIRATNA SUMAPALA", shape=ellipse];
+  "entity:16" [label="TRICIPTA MANDHALA GUMILANG", shape=ellipse];
+  "entity:17" [label="ANTHONI SALIM", shape=ellipse];
+  "ticker:BBCA" [label="BBCA", shape=box];
+
+  "entity:17" -> "ticker:BBCA" [label="1.15% (ksei)"];
+  "entity:15" -> "ticker:BBCA" [label="1.02% (ksei)"];
+  "entity:14" -> "ticker:BBCA" [label="54.94% (ksei)"];
+  "entity:16" -> "ticker:BBCA" [label="1.07% (ksei)"];
+}
+--- stderr