v1.2.1: IP-literal fast-fail + more SNIs + x.com GraphQL fix + Android SNI paste

Rollup of the three upstream-Python ports plus an Android UX polish:

- plain_tcp_passthrough: 4s connect timeout for IP literals (10s for
  hostnames). Halves Telegram DC-rotation latency when the current DC
  is DPI-dropped.
- DEFAULT_GOOGLE_SNI_POOL / DEFAULT_SNI_POOL: +maps, chat, translate,
  play, lens.google.com. More fingerprint spread, and maps/play pass
  DPI on some carriers where shorter *.google.com names don't.
- handle_mitm_request: x.com GraphQL URL truncation — strip everything
  after the first & when the path matches /i/api/graphql/.../?variables=.
  x.com's variables+features+fieldToggles blob overflows Apps Script's
  URL cap; `variables=` alone renders the timeline.
- Android SNI editor: paste-and-add now accepts a full list separated
  by whitespace / commas / newlines, dedupes, and merges with existing
  selection. Closes the "add them all at once" ask from #47.
- rlimit.rs: fence the example error log in a `text` code block so
  rustdoc stops trying to compile it.

android/app/build.gradle.kts

@@ -14,8 +14,8 @@ android {
         applicationId = "com.therealaleph.mhrv"
         minSdk = 24 // Android 7.0 — covers 99%+ of live devices.
         targetSdk = 34
-        versionCode = 120
-        versionName = "1.2.0"
+        versionCode = 121
+        versionName = "1.2.1"
 
         // Ship all four mainstream Android ABIs:
         //   - arm64-v8a      — 95%+ of real-world Android phones since 2019