fix(agent): put input schemas on tool_search cards

[TheGreatAxios]

Summary

• tool_search cards include a compact input schema on the top two ranked hits so the first MCP call is formable; up to three more hits are name + description only.
• Search still does not promote unused matches onto the tools array. Only the name the model actually calls joins the tail (promote-on-execute).
• The tool description no longer claims matches load on the next turn. The session env lists configured MCP server names.

#1226 stopped putting search hits on the wire (correct — unused Linear tools must not pad the cache prefix). The schema text still said they load next turn, and cards had no input schema, so terra and Grok never emitted mcp__linear__* names.

Verification

• bun run check passes (8154 tests, 0 fail)

[linear-code]

CL-9790