Release v0.18.4

Changes from 0.18.3 to 0.18.4

What's Changed

• fix: Default conversation system prompt recompilation routing [LET-7976] by @devanshrj in #1373
• fix(listen): normalize inbound user image payloads by @cpacker in #1374
• chore: Clean up system prompts directory [LET-7937] by @devanshrj in #1378
• feat: change lettaignore logic by @shelleypham in #1375
• fix: correct Docker pull image in outdated warning by @cpfiffer in #1380
• feat: add Terminal-Bench weekly regression workflow [LET-7791] by @devanshrj in #1232
• feat(listen): emit explicit approval and tool execution lifecycle events by @cpacker in #1381
• chore: Refactor git context gathering for session and init [LET-7906] by @devanshrj in #1379
• fix: actually enforce the max entries during index construction by @kianjones9 in #1383

Full Changelog: v0.18.3...v0.18.4