feat!: remove bootstrap cache integration

[mickvandijke]

Summary

• remove ant-core peer-cache recording hooks into the old BootstrapManager APIs
• delete bootstrap-cache E2E coverage and the direct test-only saorsa-core dev dependency
• add a persistent client peer cache at the ant data-dir client_peer_cache.json
• load all usable cached peer addresses as first-choice CLI bootstrap candidates, then append configured/hardcoded bootstrap peers as fallback only after cache candidates have had priority
• keep Client::connect exact to the bootstrap peers supplied by the caller; it no longer loads or saves the client peer cache implicitly
• filter cached CLI bootstrap candidates for --ipv4-only before selecting the startup address for each cached peer
• rely on saorsa-core client bootstrap early-return behavior to stop after 6 successful bootstrap peers, cancelling pending cache dials before fallback is reached on a healthy cache
• log when a client bootstrap cache file is found and loaded, including cached peer count, usable cached peer count, direct address count, and bootstrap candidate count
• promote live authenticated connected peers into the cache from P2PNode::peer_info(); a DHT Direct tag is no longer required for cache admission
• store only dialable peer addresses with /p2p/<peer_id> suffixes
• cap the cache at 50 peers, apply k-bucket IP diversity limits, prefer peer-id XOR spread over recency, and round-robin startup candidates across peer-id sectors
• disable the client peer cache for CLI runs using explicit network selectors: --bootstrap or --devnet-manifest
• update git imports to the pushed branch heads for saorsa-core, saorsa-transport, ant-protocol, and ant-node
• rebase the branch on current main

Timeout Scope

• saorsa-core removes the outer 6s peer dial timeout and the outer 25s connect_happy_eyeballs timeout
• direct peer dials are now bounded by the transport strategy's direct connect and handshake timeouts instead of an additional wrapper deadline

SemVer

• Major: removes the old ant-core bootstrap-cache recording hook surface and bootstrap-cache E2E/dev-dependency surface
• Minor: adds the persistent client peer cache
• Patch: cached startup now tries the full usable cache before configured/hardcoded fallback; explicit --bootstrap disables cache load/save; cache-load logging now reports cache counts
• Patch: restores Client::connect exact-bootstrap behavior by keeping implicit peer-cache load/save out of that API
• Patch: honors --ipv4-only for cached CLI bootstrap candidates
• Patch: removes redundant outer direct-dial timeouts in saorsa-core and updates git imports to the pushed dependency commits
• Patch: cache retention now prioritizes peer-id keyspace spread ahead of recency while still enforcing IP diversity limits
• Patch: cache promotion now records live authenticated connected peers rather than requiring DHT Direct-tagged routing-table entries

Git Imports

• saorsa-core: ac285f212185486b1d1ee6eee33932865413f42f
• saorsa-transport: 00447926f8847d5de99c271fb689740f749177f6
• ant-protocol: 6bc35372986474fa9f31844b034790d0b84ffb97
• ant-node: 265d6a8fad1d16a540f8bf66f319ac9afc97a4ed

Related PRs

• saorsa-transport: feat!: remove bootstrap cache saorsa-transport#86
• saorsa-core: feat!: remove bootstrap cache manager saorsa-core#124
• ant-protocol: feat!: depend on saorsa-core bootstrap-cache removal ant-protocol#9
• ant-node: feat!: depend on bootstrap-cache removal chain ant-node#119

Live Cache Checks

• download-126.log: cache promotion saw connected_peers=543, cacheable_peers=543, cacheable_addresses=552, normalized to cached_peers=50, direct_addresses=50
• download-127.log: loaded cached_peers=50, reached bootstrap target before fallback pressure, then refreshed from connected_peers=536, cacheable_peers=536, cacheable_addresses=544, normalized to cached_peers=50, direct_addresses=50
• current cache has 50 peers, 50 addresses, no empty-address peers, matching /p2p/<peer_id> suffixes, all 16 peer-id sectors represented, exact IP max 2, and subnet counts within the configured diversity limit

Verification

• cargo check --locked -p ant-core --features devnet
• cargo check --locked -p ant-cli
• cargo fmt --all -- --check
• cargo clippy --locked --all-targets --all-features -- -D warnings
• cargo test --locked -p ant-core peer_cache --lib
• git diff --check
• cargo fmt --all -- --check in ../saorsa-core
• cargo check in ../saorsa-core
• cargo clippy --all-targets --all-features -- -D warnings in ../saorsa-core
• cargo check in ../ant-protocol
• cargo check in ../saorsa-node

BREAKING CHANGE: removes ant-core bootstrap-cache recording hooks and the bootstrap-cache E2E/dev-dependency surface.