smartcontract: add TopologyInfo account, flex-algo state, and topology processors

[ben-malbeclabs]

Summary of Changes

• Adds TopologyInfo onchain account (RFC-18 flex-algo) with admin_group_bit, flex_algo_number, and TopologyConstraint; creates AdminGroupBits resource extension singleton for bit allocation
• Adds four new foundation-only instructions (107–110): CreateTopology, DeleteTopology, ClearTopology, BackfillTopology
• Extends Link with link_topologies (Vec) and link_flags (LINK_FLAG_UNICAST_DRAINED); extends Tenant with include_topologies; adds flex_algo_node_segments to Interface V3
• ActivateLink now requires the unicast-default topology account and auto-tags the link into it
• UpdateLink gains foundation-gated link_topologies update and contributor-gated unicast_drained flag

Diff Breakdown

Category	Files	Lines (+/-)	Net
Core logic	15	+735 / -34	+701
Scaffolding	49	+377 / -0	+377
Tests	23	+3,712 / -39	+3,673

Majority of prod lines are new — the scaffolding is mechanical struct field additions (link_topologies: vec![], include_topologies: vec![], flex_algo_node_segments: vec![]) across CLI, SDK, activator, and client to keep the workspace compiling.

Key files (click to expand)

• smartcontract/programs/doublezero-serviceability/src/state/interface.rs — adds Interface V3 discriminant with flex_algo_node_segments: Vec<FlexAlgoNodeSegment>; V1/V2 accounts default to empty vec via unwrap_or_default()
• smartcontract/programs/doublezero-serviceability/src/state/topology.rs — new TopologyInfo account: admin_group_bit (u8), flex_algo_number (128+bit), TopologyConstraint (IncludeAny/IncludeAll/Exclude)
• smartcontract/programs/doublezero-serviceability/src/processors/topology/ — five new processors: create (allocates AdminGroupBit, validates IdRange 1–127), delete, clear (removes topology from all links), backfill (allocates FlexAlgoNodeSegment on all device interfaces)
• smartcontract/programs/doublezero-serviceability/src/processors/link/update.rs — adds foundation-gated link_topologies update (validates each topology account onchain) and contributor-gated unicast_drained flag (LINK_FLAG_UNICAST_DRAINED bit 0)
• smartcontract/programs/doublezero-serviceability/src/processors/link/activate.rs — requires unicast_default_topology_account as a mandatory account; auto-tags new link into the unicast-default topology on activation
• smartcontract/programs/doublezero-serviceability/src/processors/globalconfig/set.rs — creates AdminGroupBits ResourceExtension PDA on global config initialization
• smartcontract/programs/doublezero-serviceability/src/state/link.rs — adds link_topologies: Vec<Pubkey>, link_flags: u64, and LINK_FLAG_UNICAST_DRAINED = 0x01
• smartcontract/programs/doublezero-serviceability/src/instructions.rs — registers four new instruction variants (CreateTopology=107, DeleteTopology=108, ClearTopology=109, BackfillTopology=110)

Testing Verification

• make rust-lint and make rust-test pass clean on this branch
• topology_test.rs (~2,400 lines) covers all four topology processors: create/delete/clear/backfill, including error paths (duplicate names, out-of-range bits, unauthorized signers, invalid topology accounts), segment allocation, and multi-topology backfill
• Existing link_wan_test.rs, tenant_test.rs, and telemetry tests updated to account for the new mandatory unicast_default_topology_account in ActivateLink
• This is PR 1 of 4 for RFC-18; see rfcs/ for the full specification. PRs 2–4 (topology CLI, link/tenant CLI extensions, SDKs/activator) follow and depend on this foundation