[REFACTOR] Deprecate context command — redundant with query

[Wolfvin]

Problem

context and query return nearly identical data for the same symbol:

• query cmd_scan: returns node + callers + callees + pagination + confidence
• context cmd_scan: returns {status, found, symbol, workspace} — a strict subset of query output

context adds no information that query does not already provide. Users querying both get confusion about which to use.

Expected Fix

• Deprecate context with a message: 'Use query instead — it returns the same data plus callers/callees graph'
• Remove in next major version
• Update MCP server tool list accordingly (tool count will drop from 62 to 61)