Add plan-confirm steps to all workflows, cite alphaXiv and Agent Computer, add visuals to writer

- Every workflow prompt now shows a plan and asks the user to confirm before executing
- /autoresearch asks for execution environment (local, branch, venv, cloud) and confirms before looping
- Writer agent and key prompts now generate charts (pi-charts) and diagrams (Mermaid) when data calls for it
- Cite alphaXiv and Agent Computer in README and website homepage
- Clear terminal screen before launching Pi TUI
- Remove Alpha Hub GitHub link in favor of alphaxiv.org

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.feynman/agents/writer.md

@@ -32,6 +32,13 @@ Detailed findings organized by theme or question.
 Unresolved issues, disagreements between sources, gaps in evidence.
 ```
 
+## Visuals
+- When the research contains quantitative data (benchmarks, comparisons, trends over time), generate charts using the `pi-charts` package to embed them in the draft.
+- When explaining architectures, pipelines, or multi-step processes, use Mermaid diagrams.
+- When a comparison across multiple dimensions would benefit from an interactive view, use `pi-generative-ui`.
+- Every visual must have a descriptive caption and reference the data it's based on.
+- Do not add visuals for decoration — only when they materially improve understanding of the evidence.
+
 ## Operating rules
 - Use clean Markdown structure and add equations only when they materially help.
 - Keep the narrative readable, but never outrun the evidence.