[Rules] Support nested AND / OR / NOT condition groups

[emi-ran]

Feature

Support nested AND / OR / NOT condition groups. Current Automation.conditions: List<RuleCondition> has flat AND semantics, so it cannot express: Wi-Fi = Home AND (time = night OR battery < 20%).

Proposed model

• Replace or version the flat list with a serializable condition expression tree: AllOf, AnyOf, Not, and leaf RuleCondition.
• Preserve existing rules by migrating each non-empty flat list to AllOf(leaves).
• Put expression evaluation in a pure engine component with short-circuit semantics and unit tests.
• Build a bounded Compose editor supporting grouping, reorder, delete, and visible nesting. Avoid arbitrary complexity if depth must be capped; document cap.
• Export/import must preserve the expression tree and retain current encrypted-backup validation-before-mutation guarantees.

Acceptance criteria

• Existing rules preserve exact behavior after migration.
• User can create Wi-Fi = Home AND (night OR battery below 20%) and a NOT group.
• Invalid empty groups cannot be saved.
• History/rule detail show a human-readable expression without sensitive values.

Verification

• Migration fixtures for old JSON, current export/import, malformed groups, and nested evaluation.
• Test repeated event, cooldown, permission-denial, and no-match paths on Xiaomi 15T Pro / HyperOS 3.