[orc] TASK-016: Knowledge exploration page

[randalmurphal]

Task: Knowledge exploration page

Design doc: docs/plans/2026-02-05-development-os-design.md
Section: "Component 6: Web UI" → "Knowledge Page"

New top-level page for exploring what orc knows about the codebase.

Search:

• Natural language search input
• Calls knowledge.Service.Query() via API
• Preset selector (standard, fast, deep, graph-first, recency)

Results rendering:

• Mixed result types: code nodes, findings, decisions, patterns
• Each result shows: type icon, file path, content snippet, score
• Code results: syntax highlighted, line numbers, last modified by task
• Finding results: severity badge, status (fixed/open), reviewer agent
• Decision results: initiative link, rationale
• Pattern results: member count, canonical example link
• "Discuss" action on every result → opens thread with that context

Insights panel:

• Hot files: files with highest retry rates (bar chart or list)
• Recurring patterns: recent patterns detected by orchestrator
• Constitution updates: recent changes with source (orchestrator/manual)
• Link to full learning report (orc learn output)

Empty state:

• When knowledge layer is not enabled or not indexed
• Guide: "Run orc knowledge start && orc index to get started"

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Created by orc workflow execution.