v0.3.29 — ToolSearch propagation receipts

Adds an executable ToolSearch propagation receipt fixture for Claude Code-style subagent MCP bugs where policy, tools frontmatter, and runtime filtering can be conflated.\n\nNew public artifacts:\n- examples/context-input-evidence/sample-subagent-toolsearch-propagation-log.jsonl\n- examples/context-input-evidence/convert-subagent-toolsearch-propagation-log.mjs\n- examples/context-input-evidence/subagent-toolsearch-propagation-receipt.ndjson\n- examples/context-input-evidence/subagent-toolsearch-propagation-otel-trace.json\n\nThe fixture emits privacy-safe evidence for spawn path, tools declaration shape, ToolSearch declared/exposed state, parent/subagent MCP server buckets, loaded/deferred tool-definition buckets, and filter reason without raw schemas, prompts, paths, or tool declarations.