runtime/v0.18.0

NOTE: These notes are inclusive of all preview releases in the v0.18.0 series.

Related to new Modus agents feature:

• feat: initial implementation of Modus Agents #840
• feat: persistence and lifecycle improvements for Modus Agents #843
• fix: reflection error in runtime when starting agent #845
• fix: trigger events correctly during agent reload #846
• feat: list agents on health endpoint #865
• feat: add agent management APIs #866
• feat: stream agent events via subscriptions #875
• chore: rename agent lifecycle methods and APIs #858
• fix: address agent lifecycle issues #881
• fix: remove ack event from SSE stream #884
• feat: add kubernetes secrets provider and API to read secrets #885
• fix: start agents synchronously, and add examples setting data on start #890
• feat: cluster mode #895
• fix: improve cluster resiliency #900
• fix: more cluster resiliency improvements #901
• fix: adjust cluster sync settings and delays #902
• feat: distribute actors across cluster when restoring on startup #907

Other items:

• feat: delete collections features #872
• feat: enforce WASI reactor mode #859
• feat: return user and chat errors in API response #863
• feat: "start" and "stop" are now mutation prefixes #889
• fix: resolve deadlocks related to open inbound http connections #891
• fix: use millisecond precision in timestamps #892
• fix: ensure valid UTF8 byte sequence in HTTP response #904
• fix: time zone retrieval and logging #906
• fix: update dockerfile to include legacy time zones #909