feat(bing): v2 panels — striking distance, queries/pages tables, tiles, get_bing_queries

[mlava]

Builds the "Future directions" section of specs/0009-bing-webmaster-integration.md on the fork while the upstream proposal (every-app#150) awaits a maintainer response. Fork-only; the clean v1 upstream branch is untouched and unaffected.

What's included

• Striking distance panel (default tab): aggregated queries at average position 5–20 sorted by impressions, with row selection + Copy / Save-as-keywords, mirroring the Search Console panel minus the page column (Bing's GetQueryStats has no page dimension).
• Queries and Pages tables: sortable, client-paginated, whole-window clicks / impressions / CTR / position.
• New tiles: CTR and impression-weighted average position join Clicks/Impressions. Clicks/Impressions/CTR get a "vs prior period" delta computed client-side by half-splitting the dense daily series (Bing controls the window; the tooltip states the exact ranges compared). Avg position deliberately has no delta — it comes from sampled data with no reliable sub-windows.
• MCP tool get_bing_queries: dimension (query|page), strikingDistanceOnly, limit 1–500. Unmetered read, registered next to get_bing_performance.

Data-honesty constraints (from the spec)

• GetQueryStats/GetPageStats rows are SAMPLED (~16 dates over ~5 months) — everything is aggregated over the whole window; no date picker, no trend charts, no device/country filters. The tables carry a caption saying so.
• Position is the impression-weighted mean of AvgImpressionPosition; AvgClickPosition (−1 when unclicked) is ignored. Rows with non-positive positions still contribute traffic but not position weight.
• Both endpoint shapes were probed live on 2026-07-25 (recorded in the spec's Consequences) — no new probing needed.

Not included

No DB/schema changes, no edits to GSC files (only imports of already-exported helpers: formatCtr/formatPosition/formatCount, TabButton, table components).

Verification

• 842 tests pass (pnpm test), including new suites for bingClient stats methods, aggregation math (boundary cases 4.9/5/20/20.1), the half-split comparison, BingService.getQueryReport, and the MCP tool.
• pnpm ci:check and vite build clean.
• ⚠️ Not yet clicked in a running app against a live Bing connection — local dev cannot complete Bing OAuth (localhost redirect refused). Verify on the deployment after merge: tiles show CTR/position with deltas, all three tabs populate, save-keywords works, and get_bing_queries returns rows over MCP.

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