Add LLM tool-calling and MCP server spikes

Add two research spike documents: docs/spikes/LLM_TOOL_CALLING_RESEARCH.md (comprehensive, format-agnostic pipeline for ingesting attachments, extracting structured research instructions, OCR/parse strategies, validation, confidence scoring, planning templates, QC checks, and command-line/tool examples) and docs/spikes/MCP_SERVER_RESEARCH.md (SPIKE 619: extraction of requirements from the MCP server prompt, explicit deliverables, constraints like GP-06, assumptions, prioritized research plan, milestones, traceability map, and prototype/test recommendations).

Author: Chris0Jeky