web: deep-link auto-connect (?serverUrl&transport&autoConnect) + machine-readable connection status

[cliffhall]

Summary

URL-driven auto-connect with a machine-readable status surface, so a driver can reach a connected inspector with one navigate:

http://127.0.0.1:6274/?serverUrl=<url>&transport=http|sse&autoConnect=<token>

• parseDeepLink() / deepLinkParseStatus() in a new clients/web/src/utils/deepLink.ts: serverUrl restricted to http(s) (rejects javascript:/data:/file:); autoConnect must equal the per-launch MCP_INSPECTOR_API_TOKEN (CSRF gate — same exposure as the existing ?MCP_INSPECTOR_API_TOKEN= param); stable deep-link server id so reloads reconnect to the same row.
• App.tsx: ensure/connect effects — upsert the full server config (not just the URL), then connect via a fresh closure; connectErrorMessage records connection-level failures.
• InspectorView header: data-testid="connection-status" with data-status, data-error-message, and data-deeplink="parsed|rejected|none" so drivers can waitForSelector and read failure reasons without scraping toasts.

Why

Reaching a connected inspector today takes several manual steps; automation has no deterministic signal for "connected" or "why not". This implements the v2 version of #1183 (?autoConnect query param).

Reference implementation (PR #1510)

Re-implement informed by these changes at 33fac3f:

• clients/web/src/utils/deepLink.ts — DeepLink, parseDeepLink(), deepLinkParseStatus(), deepLinkConfigEquals(), DEEP_LINK_SERVER_ID (+179)
• clients/web/src/utils/deepLink.test.ts — parser/security tests (+199)
• clients/web/src/App.tsx — serversRef, ensure/connect effects, recordConnectError()
• clients/web/src/components/views/InspectorView/InspectorView.tsx — header data attributes, deepLink/deepLinkStatus/connectErrorMessage props

Depends on

• Web: migrate auth store to shared /store API (RemoteOAuthStorage parity with TUI/CLI) #1548 — web OAuth storage parity (so a deep-linked OAuth-gated server can reuse stored credentials)

Wave 4 — after the Wave 2/3 lanes. The openApp/appArgs/autoOpen params are a separate follow-up issue.

Refs #1183.

Notes

• The token gate is the security boundary: a launcher/agent that knows the token can mint links; a third-party page cannot. Keep the validation inside parseDeepLink() so a returned DeepLink is proof of validation.
• Document the deep-link scheme and the data-* contract in clients/web/README.md.
• Coverage gate ≥90 on all four dimensions.

Part of the PR #1510 decomposition (see tracking issue).