feat: expose Smart sticky sessions

[eyaeya]

Dependency chain

This PR is part of a three-PR change set for Smart strategy: sticky-sessions support:

1. OIX core support: vernesong/mihomo-oix#6
2. Matching non-OIX core support: vernesong/mihomo#10
3. OpenClash LuCI/YAML wiring, this PR: vernesong/OpenClash#5198

This OpenClash PR depends on compatible core support. It only exposes and writes strategy: sticky-sessions; the actual affinity behavior must be implemented by the selected core.

Compatibility dependency by selected core:

• OIX users need vernesong/mihomo-oix#6, or an equivalent OIX core release, before enabling this option.
• Non-OIX users need vernesong/mihomo#10, or an equivalent non-OIX core release, before enabling this option.

Recommended merge/release order:

1. Merge/release core support: vernesong/mihomo-oix#6 and vernesong/mihomo#10.
2. Merge this OpenClash PR after supported cores can parse and enforce Smart strategy: sticky-sessions.

On older cores, generated YAML containing Smart strategy may fail config parsing. That is why this PR keeps the option opt-in, leaves defaults unchanged, and includes LuCI wording that calls out the core dependency.

Summary

Expose Smart strategy: sticky-sessions in OpenClash without changing existing defaults.

This PR only wires configuration and LuCI. The actual sticky behavior must be provided by a compatible Smart-capable core.

Root cause

Router-side investigation found that OpenClash had partial Smart strategy plumbing but no working end-to-end path:

• yml_groups_get.sh could import a Smart YAML strategy into UCI as strategy_smart.
• yml_groups_set.sh did not read or write strategy_smart, so exporting/regenerating YAML dropped it.
• LuCI exposed strategy only for load-balance, not Smart.
• Smart auto-switch converted url-test/load-balance groups to smart and added LightGBM/collect/prefer-ASN fields, but never wrote a Smart strategy.
• Current cores before the paired core PRs do not parse Smart strategy, so OpenClash must not present this as an OpenClash-only fix.

Design

• Add per-group strategy_smart LuCI option for Smart groups.
• Only offer sticky-sessions for Smart groups; do not offer round-robin or consistent-hashing because those remain load-balance strategies.
• Read strategy_smart in yml_groups_set.sh and write strategy: sticky-sessions only when explicitly set.
• Add global smart_strategy, defaulting to 0, for Smart auto-switch/overwrite flows.
• Pass smart_strategy into yml_rules_change.sh and only write group['strategy'] = 'sticky-sessions' when the user explicitly selects it.
• Keep default behavior unchanged: no Smart group receives strategy unless explicitly configured.
• Restrict global smart_strategy to groups newly converted by Smart auto-switch; existing Smart groups continue to use their per-group strategy_smart setting.
• Add a small offline regression script checking the critical wiring paths.

Validation

• bash -n luci-app-openclash/root/usr/share/openclash/*.sh luci-app-openclash/root/etc/init.d/openclash tests/openclash_smart_strategy_test.sh
• tests/openclash_smart_strategy_test.sh
• git diff --check HEAD^ HEAD

[Pluviophile714]

用ai用魔怔了？

[eyaeya]

用ai用魔怔了？

@Pluviophile714
如果是 PR 质量问题，请明确指出。
如果是情绪问题，那么，烦请大佬你出手解决 Smart 模式下 strategy: sticky-sessions 失效的问题，例如短时间内 chatgpt.com:443：170 条连接命中过 9 个节点。我会认真阅读大佬你的PR。