[uptime-kuma] Chart Update

[mvprowess]

Version path: 1.23.13 → 1.23.17 (security patches) → 2.1.0

⚠️ This is a major version upgrade (chart version: 1.0.0 boundary). The v1→v2 database migration can take hours on large instances and must not be interrupted. Users must back up their /app/data directory before upgrading.

• 1.23.14 — SSTI security fix in notification templates
• 1.23.16 — LFI fix via Real-Browser monitor (CVE-2024-56331)
• 1.23.17 — final v1 patch; :latest Docker tag still points to v1
• 2.0.0 — major breaking: JSON backup removed, DNS cache removed, SMTP templates → LiquidJS (case-sensitive), Alpine images dropped, default retries 1→0, badge duration restricted
• 2.1.0 — domain expiry monitoring, Jira/Google Sheets notifications, DB pool/SSL config

Changes required (chronological):

• 1.23.9 — Add UPTIME_KUMA_WS_ORIGIN_CHECK to values if not already present (important for K8s Ingress deployments)
• 2.0.0 — Update image tag to :2 (major version pin — do not pin a specific 2.x.x patch)
• 2.0.0 — Add MariaDB database section to values: UPTIME_KUMA_DB_TYPE, UPTIME_KUMA_DB_HOSTNAME, UPTIME_KUMA_DB_PORT, UPTIME_KUMA_DB_NAME, UPTIME_KUMA_DB_USERNAME, UPTIME_KUMA_DB_PASSWORD
• 2.0.0 — Add UPTIME_KUMA_NOTIFICATION_PROXY to values
• 2.1.0 — Add UPTIME_KUMA_DB_SOCKET, UPTIME_KUMA_DB_POOL_MAX_CONNECTIONS, UPTIME_KUMA_DB_SSL, UPTIME_KUMA_DB_CA
• 2.1.0 — Add Docker secrets variants: UPTIME_KUMA_DB_PASSWORD_FILE, UPTIME_KUMA_DB_USERNAME_FILE, UPTIME_KUMA_DB_CA_FILE
• Add note to README/NOTES.txt: SSTI (1.23.14) and LFI (1.23.16) security fixes exist for users still on 1.23.13
• Add migration guidance to README/NOTES.txt: back up /app/data before upgrading; do not interrupt migration; :latest tag still points to v1
• Document v2 breaking changes in README: JSON backup removed, DNS cache removed, SMTP now uses LiquidJS (variables are case-sensitive), Alpine images discontinued
• Bump appVersion to 2.1.0
• Bump chart version to 1.0.0