fix(ai): normalize tool result history

[rekram1-node]

Summary

• normalize local tool history once before cache policy and protocol lowering
• synthesize error results for unresolved calls before the next user or assistant message
• leave trailing calls pending for the caller to execute
• replace truly empty outputs while preserving whitespace, media-only output, unmatched results, and provider-executed history
• reconcile matching result names with their call identity

Testing

• bun test --only-failures from packages/ai (914 passed, 25 skipped)
• bun test test/tool-history.test.ts test/compile.test.ts from packages/ai
• bun typecheck from packages/ai
• Prettier and git diff --check