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/help-ownership.golden

@@ -0,0 +1,58 @@
+exit: 0
+--- stdout
+Ownership intelligence (KSEI + Bing).
+
+Preferred bootstrap path:
+  1. Run `idx ownership sync` to install or refresh a maintained SQLite snapshot.
+  2. If no snapshot manifest is available, run `idx ownership discover` and then `idx ownership import --url <pdf-url>`.
+  3. Local `.xlsx`, `.pdf`, `.zip`, and `.txt` imports remain available for manual or fallback workflows.
+
+Usage: idx ownership [OPTIONS] <COMMAND>
+
+Commands:
+  discover       Discover the latest IDX-hosted ownership report URLs
+  import         Import ownership data directly from source files
+  sync           Install or refresh a maintained ownership SQLite snapshot
+  ticker         Show all holders for a ticker (KSEI + Bing combined)
+  entity         Show all holdings for an entity across tickers
+  search         Search entities by name
+  cross-holders  Rank entities by cross-ownership breadth
+  concentration  Rank tickers by ownership concentration
+  flow           Show Bing institutional flow for a ticker
+  changes        Diff two KSEI releases
+  graph          Ownership network graph
+  resolve        Manual entity resolution workflow
+  releases       List imported KSEI releases
+  help           Print this message or the help of the given subcommand(s)
+
+Options:
+  -o, --output <OUTPUT>
+          Output format
+          
+          [possible values: table, json]
+
+      --no-color
+          Disable colored output
+
+  -q, --quiet
+          Suppress non-essential output
+
+  -v, --verbose...
+          Increase verbosity (-v, -vv)
+
+      --offline
+          Run without network requests
+
+      --no-cache
+          Bypass local cache
+
+  -h, --help
+          Print help (see a summary with '-h')
+
+Examples:
+  idx ownership sync
+  idx ownership sync --manifest /path/to/ownership-snapshot-manifest.json
+  idx ownership discover --limit 1
+  idx ownership import --url <pdf-url>
+  idx ownership releases
+--- stderr