docs: refresh planner priorities for 4229

[asim]

Summary:

• Drop completed streaming item ai: broaden provider streaming coverage through chat and A2A #4217 after agent: cancel StreamAsk on close #4226 merged.
• Promote OpenTelemetry run-history spans and keep examples wayfinding next to balance agentic depth with developer adoption.

Testing:

• git diff --check
• go build ./...
• go test ./... (environment failures: provider/loopback tests)
• golangci-lint run ./...

Closes #4229

[Copilot]

Pull request overview

Updates the autonomous planner’s ranked work queue to reflect recently completed streaming work and to promote the next highest-priority agent observability and adoption tasks.

Changes:

• Removes the completed streaming coverage queue item (#4217), which was closed via merged PR #4226.
• Promotes “OpenTelemetry spans from agent run history” to the top priority and reorders remaining items accordingly.

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