fix: make Wordstat view content gate soft

[axisrow]

Closes #13

Summary

• make table-text comparison in _select_view a separate required=False corroboration after the sole hard readiness gate (checked, download button, and table rows where applicable)
• remove _is_view_active and retain the two-attempt timeout budget
• preserve a table snapshot before the final map view so the next batch phrase gets its soft phrase-change nudge
• document the soft-signal invariant and add regressions for both behaviors

Verification

• uv run pytest — 112 passed
• uv run ruff check . — passed
• CDP endpoint http://127.0.0.1:9223: one-phrase collection and close-pair batch (ремонт квартир, ремонт квартир цена) completed after the rebase.

Live comparison with main

No row-count regression observed. This branch produced top_popular: 0, top_related: 0, dynamics: 24, and regions: 933 for ремонт квартир; the close-pair batch's second phrase produced 0, 0, 24, 692. The zero-row top reports reproduce on main before this change (for example, prior PR #7-era runs: купить телефон = 0/0/24/950, новогодние подарки = 0/0/24/765) and are documented as Wordstat behavior outside issue #13.