Via grants compile filter rules that depend on the node's route state
(SubnetRoutes, ExitRoutes). Without per-node compilation, these rules
were only included in the global filter path which explicitly skips via
grants (compileFilterRules skips grants with non-empty Via fields).
Add a needsPerNodeFilter flag that is true when the policy uses either
autogroup:self or via grants. filterForNodeLocked now uses this flag
instead of usesAutogroupSelf alone, ensuring via grant rules are
compiled per-node through compileFilterRulesForNode/compileViaGrant.
The filter cache also needs to account for route-dependent compilation:
- nodesHavePolicyAffectingChanges now treats route changes as
policy-affecting when needsPerNodeFilter is true, so SetNodes
triggers updateLocked and clears caches through the normal flow.
- invalidateGlobalPolicyCache now clears compiledFilterRulesMap
(the unreduced per-node cache) alongside filterRulesMap when
needsPerNodeFilter is true and routes changed.
Updates #2180
ccd284c0a5