Dashboard & widget CRUD hits Public API & MCP; dense traces no longer freeze

What's Changed

Features

• feat(sessions): allow metadata filtering on v4 by @nimarb in https://github.com/langfuse/langfuse/pull/15138
• feat(worker): write deprecation notice into blob export for legacy sources (LFE-10896) by @niklassemmler in https://github.com/langfuse/langfuse/pull/15068
• feat(seeder): add base64 payload style for huge data-URI IO (LFE-10152) by @nkabardin in https://github.com/langfuse/langfuse/pull/15054
• feat(api, mcp): Add dashboard & widget CRUD to Public API & MCP (unstable) by @LysanderKie in https://github.com/langfuse/langfuse/pull/15080

Fixes

• fix(auth): guard callback-url redirect against malformed callbackUrl (500s) by @Steffen911 in https://github.com/langfuse/langfuse/pull/15132
• fix(events): force events_full for truncation-sensitive filters (LFE-10779) by @niklassemmler in https://github.com/langfuse/langfuse/pull/15069
• fix(automations): suppress spurious 404 toast on delete, instant not-found detection by @wochinge in https://github.com/langfuse/langfuse/pull/15147
• fix(agent): Improve tool call styling by @bezbac in https://github.com/langfuse/langfuse/pull/15084
• fix(trace): budget aggregated graph layout so dense traces can't freeze the tab (LFE-10988) by @nkabardin in https://github.com/langfuse/langfuse/pull/15153
• fix(api): handle legacy traces widgets on unstable dashboard-widgets API by @LysanderKie in https://github.com/langfuse/langfuse/pull/15154

Chores

• chore(deps): bump nodemailer to 9.0.3 by @nimarb in https://github.com/langfuse/langfuse/pull/15102
• perf(shared): replace lossless-json parser with native JSON.parse source reviver by @Steffen911 in https://github.com/langfuse/langfuse/pull/15104

Full Changelog: https://github.com/langfuse/langfuse/compare/v3.215.0...v3.216.0