fix(baoyu-post-to-wechat): make remote-api work under Bun & validate config strictly

The initial remote-api implementation (3b29f3c) relied on
`https.request({ agent: SocksProxyAgent })` to route token/upload/draft
calls through the SSH tunnel. Bun's `https.request` does not honor
Node's `http.Agent` contract, so the agent was silently bypassed and
requests still originated from the local IP — defeating the entire
IP-allowlist purpose. Two follow-on issues compounded it: tests read
the real `~/.baoyu-skills/.env` because Bun's `os.homedir()` ignores
test-time `process.env.HOME` mutations, and invalid config values were
silently coerced to defaults.

P1 — Bun-portable SOCKS routing:
- Drop `socks-proxy-agent` dependency. Add `socks` direct dep.
- New `wechat-socks-http.ts`: raw TCP via `SocksClient.createConnection`
  + `tls.connect({ socket, servername })` + hand-built HTTP/1.1 (status
  line parser, case-insensitive headers, chunked & content-length body
  framing). Works identically under Node and Bun because it avoids
  `http.Agent` entirely.
- Rewrite `wechat-http.ts` as a fetch-based local client and expose
  a `WechatClient = (url, init?) => Promise<WechatHttpResponse>`
  functional abstraction.
- `wechat-api.ts`: replace `agent?: http.Agent` with
  `client: WechatClient = wechatHttp` on the five HTTP-touching
  functions; `withSshTunnel` now yields a `WechatClient`.
- New `wechat-socks-http.test.ts` stands up a real SOCKS5 server
  stub + HTTP echo server and asserts `connectionCount === 1`,
  proving bytes actually traverse the proxy under both runtimes.

P2 — `HOME` honored under Bun:
- `homeDir()` reads `process.env.HOME` / `USERPROFILE` first, falling
  back to `os.homedir()`. `loadWechatExtendConfig` and `loadCredentials`
  use it, restoring test isolation.

P3 — Strict config validation:
- Replace lenient `toOptional*` helpers with `parsePort` /
  `parsePositiveInt` / `parseStrictHostKeyChecking` that throw with
  the key name. `loadWechatExtendConfig` only catches file-read
  errors so parse errors surface to the caller. Flip the corresponding
  test cases.

Verification:
- `npm test`: 261/261 pass.
- `bun test` in `scripts/`: 39/39 pass.

Co-authored-by: Dame5211 <1079825614@qq.com>

skills/baoyu-post-to-wechat/scripts/bun.lock

@@ -9,7 +9,7 @@
         "baoyu-chrome-cdp": "^0.1.0",
         "baoyu-md": "^0.1.0",
         "jimp": "^1.6.0",
-        "socks-proxy-agent": "^10.0.0",
+        "socks": "^2.8.9",
       },
     },
   },
@@ -88,8 +88,6 @@
 
     "@types/unist": ["@types/unist@3.0.3", "", {}, "sha512-ko/gIFJRv177XgZsZcBwnqJN5x/Gien8qNOn0D5bQU/zAzVf9Zt3BlcUiLqhV9y4ARk0GbT3tnUiPNgnTXzc/Q=="],
 
-    "agent-base": ["agent-base@9.0.0", "", {}, "sha512-TQf59BsZnytt8GdJKLPfUZ54g/iaUL2OWDSFCCvMOhsHduDQxO8xC4PNeyIkVcA5KwL2phPSv0douC0fgWzmnA=="],
-
     "ansi-colors": ["ansi-colors@4.1.3", "", {}, "sha512-/6w/C21Pm1A7aZitlI5Ni/2J6FFQN8i1Cvz3kHABAAbw93v/NlvKdVOqz7CCWz/3iv/JplRSEEZ83XION15ovw=="],
 
     "any-base": ["any-base@1.1.0", "", {}, "sha512-uMgjozySS8adZZYePpaWs8cxB9/kdzmpX6SgJZ+wbz1K5eYk5QMYDVJaZKhxyIHUdnnJkfR7SVgStgH7LkGUyg=="],
@@ -286,8 +284,6 @@
 
     "socks": ["socks@2.8.9", "", { "dependencies": { "ip-address": "^10.1.1", "smart-buffer": "^4.2.0" } }, "sha512-LJhUYUvItdQ0LkJTmPeaEObWXAqFyfmP85x0tch/ez9cahmhlBBLbIqDFnvBnUJGagb0JbIQrkBs1wJ+yRYpEw=="],
 
-    "socks-proxy-agent": ["socks-proxy-agent@10.0.0", "", { "dependencies": { "agent-base": "9.0.0", "debug": "^4.3.4", "socks": "^2.8.3" } }, "sha512-pyp2YR3mNxAMu0mGLtzs4g7O3uT4/9sQOLAKcViAkaS9fJWkud7nmaf6ZREFqQEi24IPkBcjfHjXhPTUWjo3uA=="],
-
     "sprintf-js": ["sprintf-js@1.0.3", "", {}, "sha512-D9cPgkvLlV3t3IzL0D0YLvGA9Ahk4PcvVwUbN0dSGr1aP0Nrt4AEnTUbuGvquEC0mA64Gqt1fzirlRs5ibXx8g=="],
 
     "strtok3": ["strtok3@10.3.5", "", { "dependencies": { "@tokenizer/token": "^0.3.0" } }, "sha512-ki4hZQfh5rX0QDLLkOCj+h+CVNkqmp/CMf8v8kZpkNVK6jGQooMytqzLZYUVYIZcFZ6yDB70EfD8POcFXiF5oA=="],