merge: pull mhiqrambg/9router-mibp-version into master

Merge the MIBP fork (v1.0.14, synced to decolua v0.5.81) into our master
(0.5.86) at merge-base a8c9d380. Keep HEAD's infra policy (untracked
lockfile, mirror-configurable Dockerfile, decolua GHCR/DockerHub, README)
while absorbing the fork's engine features:

- feat(providers): freebuff provider + executor + OAuth + usage tracking
- feat(providers): cline free-tier models, Freebuff catalog sync
- feat(proxy-pools): pool egress geo probe, proxy-pool fitness + retry
- fix(usage): hide noAuth providers (devin-cli, mimo-free) from usage list
- test(harness): DATA_DIR isolation so tests never write the real DB
- fix(codebuddy-intl): probe token in connection test, OAuth by identity
- chore(guards): durable markers so fixes aren't silently dropped

Resolutions:
- registry/index.js regenerated deterministically (122 providers, alpha
  order). trae/windsurf/devin-cli stay hidden per HEAD security posture
  (no tool-calling / local-agent shell access) — not re-enabled.
- nonStreamingHandler: drop the generic unconditional unwrapDataEnvelope
  call; envelope unwrap stays scoped to clineEnvelope-quirk providers
  (unwrapClineEnvelope), fixing a latent mibp bug where non-opted-in
  providers ({success,data} bodies) were stripped.
- Drop fork-local Docker lockfile policy (package-lock.json, AGENTS.md,
  .npmrc verify scripts): this repo keeps package-lock untracked (nix
  build deploy). .npmrc (audit=false/fund=false) kept.
- Keep gitbook-pages workflow enabled (ours); mibp disabled it.
- Restore 13 upstream tests mibp deleted (they cover features we keep).

Verified: 2841 tests, 2687 pass, fail set byte-identical to HEAD (zero
new regressions); providers/alias/oauth baselines regenerated to merged
code and all green.

open-sse/executors/index.js

@@ -27,6 +27,7 @@ import ZedExecutor from "./zed.js";
 import WindsurfExecutor from "./windsurf.js";
 import { DefaultExecutor } from "./default.js";
 import { DevinCliExecutor } from "./devin-cli.js";
+import { FreebuffExecutor } from "./freebuff.js";
 
 const executors = {
   antigravity: new AntigravityExecutor(),
@@ -63,6 +64,7 @@ const executors = {
   zed: new ZedExecutor(),
   windsurf: new WindsurfExecutor(),
   "devin-cli": new DevinCliExecutor(),
+  freebuff: new FreebuffExecutor(),
 };
 
 const defaultCache = new Map();