chore(release): bump chart to 1.9.8

[LukasWodka]

Next-cycle bump after v1.9.7 shipped to prod. The staging wave that just landed (#480) couldn't cut an rc — 1.9.7 is already final — so the next dev→staging hop cuts v1.9.8-rc.1 once this merges. Rides with #481 (rootless header fix) and whatever else lands on develop.

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Note

Low Risk
Metadata-only version bump with no runtime, security, or deployment template changes.

Overview
Bumps the unified client Helm chart release metadata from 1.9.7 to 1.9.8 by updating both version and appVersion in Chart.yaml.

This is a release-cycle version bump so the next develop→staging hop can tag v1.9.8-rc.1 after merge; no chart templates, values, or application code are modified in this PR.

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[LukasWodka]

👋 Heads-up — Code review queue is at 32 / 30

Above the WIP limit. The team convention is to review existing PRs before opening new work.

Open PRs currently in Code review (oldest first):

• averaging-service#222 — fix(sklearn): unwrap Pipeline to terminal estimator before merge dispatch (Prod: Set kubeconfig context namespace after Helm install for tracebloc  #209) · author: @divyasinghds · no reviewer assigned
• averaging-service#225 — fix(averaging): fail fast + dead-letter on permission-denied weight write (release: promote develop → main (installer hardening — OOM gate, apt/needrestart fixes, drift CI) #221) · author: @divyasinghds · no reviewer assigned
• backend#1201 — docs(rfc): Data spaces & federated dataset composition (draft) · author: @LukasWodka · reviewer: @saadqbal
• backend#1217 — docs(rfc): Dataset integrity & score reproducibility (draft) · author: @LukasWodka · reviewer: @saadqbal
• backend#1261 — RFC-BACKEND-0008: board & process reset (decision RFC — for markup) · author: @LukasWodka · reviewer: @saadqbal
• backend#1284 — docs(deploy): backend deploy runbook skeleton (#1263) · author: @LukasWodka · no reviewer assigned
• backend#1293 — fix(heartbeat): tolerate unknown experiment_key in training_info (#1287) · author: @divyasinghds · no reviewer assigned
• backend#1332 — feat(check-model): allow KNN/GaussianProcess on a single-edge owned dataset (#923 follow-up) · author: @divyasinghds · no reviewer assigned
• claude-skills#14 — feat(skill): add tracebloc-frontend-app skill · author: @waqaskhanroghani · no reviewer assigned
• claude-skills#15 — feat(skill): add tracebloc-design-system skill · author: @waqaskhanroghani · no reviewer assigned

Pull from review before opening new work. (This is a nudge from the kanban WIP check, not a block.)

[divyasinghds]

Clean release-cycle bump 1.9.7→1.9.8 (version + appVersion), no template/values/code changes. Helm lint/unit/template-render all green. LGTM.