CPLAT-9497: improve remote worker session handoff

[gavin-jeong]

JIRA: https://sendbird.atlassian.net/browse/CPLAT-9497

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Summary

• Add reusable remote worker pod support with configurable context/namespace/pod/container/user/home and per-session workdir templates.
• Add remote lifecycle verbs for sync up/down, exec, phase, snapshot/restore/fork, snapshot import/export, and pull-on-stop.
• Add ccx config helpers (view, edit, path, get, set) and ccx info for matched session metadata.

Test plan

• go build ./...
• go vet ./...
• go test ./... (446 passed)
• Verified real remote sync against dlops-apne2-ahcl/coder/coder-gavin-jeong-claude-agent without deleting the pod
• Verified snapshot/restore/export/import and fixed-pod reuse against real Kubernetes pods

[jinsekim]

LGTM!

[jinsekim]

LGTM!