Broken click targets: error-codes 404, wrong YouTube footer, hhttps:// sample links

[harkiratsm]

Several clickable links on docs.dapr.io (v1.18) are wrong:

1. https://docs.dapr.io/operations/observability/metrics/metrics-overview/ → Dapr API error codes → /reference/api/error_codes/ 404. Should be /developing-applications/error-codes/.

2. Footer YouTube → https://www.youtube.com/@darpdev (wrong channel). Should be @daprdev.

3. Secrets quickstart JavaScript tab → sample repo link uses hhttps:// → #ZgotmplZ. Same typo on state-management Go tab.

4. resiliency quickstart this link has a trailing // (still 200).