Add dedicated memory v2 consolidation and read prompts

[copyberry]

Add dedicated memory v2 consolidation and read prompts

What changed

• Consolidate v2 rollout summaries into memory_summary.md without generating raw_memories.md or requiring MEMORY.md. Validate the summary's required sections and size below 10,000 UTF-8 bytes.
• Add v2 read instructions for selective history retrieval, evidence-grounded preferences, citations, and explicit memory edits. Split injected instructions into fragments to preserve the complete summary within fragment byte limits.
• Record memory citation usage in the store selected by memories.version.

Testing

Add coverage for v2 consolidation without a handbook, summary validation, version-isolated memory reads, and resetting both memory versions while preserving threads.