fix: address agent lifecycle issues

[mattjohnsonpint]

• Fixes several agent lifecycle issues, such as stopping an agent while its suspended.
• Agent activation within wasm module is now split from initialization.
• Updated agent functions for shutdown and event status.
• Added DB functions for updating status without resetting state data.
• Lots of refactoring and misc fixes.

Note, I tested with passivation enabled for suspend/restore state changes. However, I disabled it at the end because there's still an open issue with long-running tasks.

[linear]

HYP-3472 Error stopping modus agent while its suspended

[Copilot]

Pull Request Overview

This PR overhauls the agent lifecycle by centralizing lifecycle actions into a single event handler, refactors the Wasm agent actor to use discrete start/resume/suspend/stop methods with database-backed status updates, and adds a new UpdateAgentStatus helper in the DB layer.

• Introduce handleEvent/handleMessage exports and remove separate activate/shutdown in Go and AssemblyScript SDKs
• Refactor wasmAgentActor to split lifecycle into startAgent, resumeAgent, suspendAgent, stopAgent, and push status updates to the database
• Add UpdateAgentStatus in agentstate.go and tweak the wasm host config (WithSysNanosleep, disable passivation)

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
sdk/go/pkg/agents/agents.go	Replaced shutdownAgent, added handleEvent, improved Stop error handling
sdk/assemblyscript/src/assembly/exports.ts	Updated exports to use _modus_agent_handle_event
sdk/assemblyscript/src/assembly/agent.ts	Removed shutdownAgent, added handleEvent and lifecycle comments
runtime/wasmhost/wasmhost.go	Broke chain calls for clarity, added WithSysNanosleep
runtime/db/agentstate.go	Added UpdateAgentStatus, refactored DB update functions
runtime/actors/wasmagent.go	Refactored actor lifecycle into discrete methods and status updates
runtime/actors/agents.go	Updated actor spawning, StopAgent/getAgentInfo to use ensureAgentReady
runtime/actors/actorsystem.go	Disabled passivation to avoid premature actor shutdown
CHANGELOG.md	Added entry for agent lifecycle fixes
.trunk/configs/cspell.json	Added “Nanosleep” to spelling dictionary

Comments suppressed due to low confidence (2)

runtime/db/agentstate.go:68

• The nil‐engine guard was removed, so if GlobalModusDbEngine is nil this Upsert will panic or error. Consider re‐adding a check to skip or warn when the engine is unavailable.

gid, _, _, err := modusgraph.Upsert(ctx, GlobalModusDbEngine, state)

.trunk/configs/cspell.json:129

• [nitpick] The entry 'Nanosleep' may not match the lowercase nanosleep naming in code; consider aligning casing with the actual API name.

"Nanosleep",