fix(dashboard): retry singleton listen with backoff on Windows shutdown race

[Skn0tt]

When the previous dashboard instance is mid-shutdown on Windows, net.createServer().listen() can fail with EBUSY even after a failed net.connect() (because the pipe name is still transiently held by the kernel). This causes the singleton acquisition to fail rather than waiting for the previous instance to finish closing.

• Retry server.listen with exponential backoff (100ms, 200ms, 400ms, 800ms, 1600ms) when the connect-then-listen path fails
• Give up and reject after 5 retries (~3.1s total)

[github-actions]

Test results for "MCP"

30 failed
❌ [firefox] › mcp/cli-devtools.spec.ts:115 › per-part commands extract individual parts @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:138 › request* and response* commands support --filename @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:173 › response-body returns just the body @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:189 › request with out-of-range index @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:199 › tracing-start-stop @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:217 › video-start-stop @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:231 › video-chapter @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:239 › generate-locator @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:248 › highlight @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:265 › highlight --hide @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-session.spec.ts:99 › session stops when browser exits @mcp-windows-latest-firefox
❌ [firefox] › mcp/http.spec.ts:103 › http transport browser lifecycle (isolated) @mcp-windows-latest-firefox
❌ [firefox] › mcp/http.spec.ts:142 › http transport browser sigint @mcp-windows-latest-firefox
❌ [firefox] › mcp/launch.spec.ts:101 › isolated context @mcp-windows-latest-firefox
❌ [msedge] › mcp/cli-session.spec.ts:56 › close-all @mcp-windows-latest-msedge
❌ [msedge] › mcp/cli-session.spec.ts:99 › session stops when browser exits @mcp-windows-latest-msedge
❌ [msedge] › mcp/cli-session.spec.ts:113 › session reopen with different config @mcp-windows-latest-msedge
❌ [msedge] › mcp/cli-session.spec.ts:130 › workspace isolation - sessions in different workspaces are isolated @mcp-windows-latest-msedge
❌ [msedge] › mcp/cli-session.spec.ts:162 › list --all lists sessions from all workspaces @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:124 › daemon show: closing page exits the process @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:164 › should capture annotations via show --annotate @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:185 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:207 › should enter annotate mode on fresh dashboard.tsx mount with -s --annotate @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:231 › should annotate via direct browser_annotate MCP call @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:264 › should annotate when context has no fixed viewport @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:301 › should cancel browser_annotate when the MCP request is aborted @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:332 › should cancel browser_annotate when the MCP client disconnects @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:361 › should switch screencast to -s session on show --annotate @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:410 › should disengage annotate mode when --annotate client disconnects @mcp-windows-latest-msedge
❌ [msedge] › mcp/dashboard.spec.ts:477 › save recording streams WebM bytes to the chosen file @mcp-windows-latest-msedge

6874 passed, 1052 skipped

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