[ISSUE #2475] fix(ai): tolerate unavailable session storage

[yuluo-yx]

Summary

• degrade AI history hydration to empty storage when sessionStorage reads fail
• ignore removal failures after clearing pending persistence
• keep in-memory conversation behavior available under browser storage restrictions

Verification

• aiChatHistoryStore.test.ts: 10 tests passed
• targeted ESLint and Prettier checks passed
• scope check: 157 changed lines

Fixes #2475

[RockteMQ-AI]

Summary

Adds defensive error handling for session storage failures (SecurityError) in the AI chat history store, ensuring the in-memory store remains usable even when persistence fails.

Strengths:

• Graceful degradation when storage is unavailable
• Comprehensive test coverage for error scenarios
• Proper mock cleanup with restoreAllMocks()

LGTM — improves resilience of AI chat history feature.

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