## Summary
This PR enhances the handling of sensitive configuration variables by
improving masking logic and user experience when editing them. It adds
metadata-aware masking for dynamically marked sensitive variables and
clears sensitive values when entering edit mode.
## Key Changes
- **Backend masking improvements**: Updated `maskSensitiveValue()` to
accept metadata parameter, enabling masking of variables marked as
sensitive via metadata (not just predefined masking config). Sensitive
non-string values are masked as `********`.
- **Edit mode UX**: When editing a sensitive variable, the value field
is now cleared on entering edit mode to prevent exposing masked values
and ensure users intentionally provide new secret values.
- **Form state tracking**: Enhanced `useConfigVariableForm()` hook to
accept an `isEditing` parameter and properly track value changes for
sensitive variables during edit operations.
- **Input placeholder**: Updated placeholder text for sensitive variable
inputs to show `Enter a new secret value` instead of the generic
database storage message, providing clearer intent to users.
## Implementation Details
- The `maskSensitiveValue()` method now checks both predefined masking
configurations and runtime metadata to determine if a value should be
masked
- Sensitive string values use LAST_N_CHARS strategy (4 characters),
while non-string values are masked uniformly
- The form's `hasValueChanged` flag is set to true when editing
sensitive variables to ensure proper validation and submission handling
https://claude.ai/code/session_01JiTckmuVJMQWpJ7TUGwsqb
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Co-authored-by: Claude <noreply@anthropic.com>
