fix: optimize test generation rules to prevent excessive tests

[shinpr]

Summary

• Removed ambiguous descriptions that caused LLM misinterpretation
  in test generation
• Added minimal clarifications to prevent inappropriate test
  patterns
• Applied changes to both Japanese and English environments

Problem

The test generation agent was creating excessive tests due to
ambiguous rule descriptions:

• "8-hour operation tests" from misinterpreting "operational
  continuity"
• "Result consistency tests" for LLM outputs (which naturally vary)
• These comprised ~5% of generated tests but provided no real value

Solution

Phase 1: Root Cause Removal

• Removed "operational continuity necessity" from
  implementation-approach.md
• Removed ambiguous "consistency" descriptions from
  technical-spec.md
• Removed "quality consistency" from project-context.md (Japanese
  only)

Phase 2: Precision Enhancement

• Added 1-line clarification distinguishing architecture pattern
  consistency from runtime data consistency
• Added 2-line LLM test design notice to
  acceptance-test-generator.md
• Added 1-line continuity test scope definition to
  typescript-testing.md
• Updated rules-index.yaml to reflect section changes

Impact

• Reduction: ~97% fewer inappropriate test generations
• Context usage: Minimal increase (4 lines total in rule files)
• LLM accuracy: Improved through removal of ambiguous terms