feat(mosh): integrate MoshCatty pure Rust client (no Cygwin legacy) (#2085)

* feat(mosh): default bundled client to MoshCatty releases

Wire Netcatty packaging and npm run dev to pull pure Rust mosh-client
binaries from binaricat/MoshCatty (moshcatty-* tags), document the cutover,
and mark the old Cygwin Windows fetch path as legacy-only.

* fix(mosh): accept pure MoshCatty packages (exe-only, no dlls/terminfo)

Align fetch/packaging with MoshCatty pure-Rust releases: require only
mosh-client[.exe], treat Cygwin dll bags and terminfo as optional legacy
layout. Document moshcatty-0.1.1 (ConPTY Ctrl+C + static MSVC CRT).

* refactor(mosh): drop Cygwin legacy; MoshCatty-only pipeline

Remove FluentTerminal/mosh-bin fallbacks, build-mosh C++ CI, and
dll/terminfo runtime helpers. Fetch accepts only moshcatty-* pure
binaries; packaging ships a single mosh-client per platform.

* docs: align ET checklist and et README with MoshCatty-only mosh

Update mosh template references after removing Cygwin build pipeline and
legacy fallbacks. Point ET packaging notes at fetch-mosh / MoshCatty
instead of deleted build-mosh-binaries workflow.

* docs(mosh): require MoshCatty 0.1.2+ for Linux glibc floors

Codex review vs main: defaulting to MoshCatty Linux binaries built on
ubuntu-latest required GLIBC 2.34, above Netcatty's package floors
(x64 2.28 / arm64 2.31). Document the floors, prefer moshcatty-0.1.2+,
and drop trailing whitespace in the design note. Upstream MoshCatty
release CI now builds in almalinux:8 / debian:bullseye with assert.

* fix(mosh): reject MoshCatty releases below 0.1.2

Codex re-review: docs alone still allowed MOSH_BIN_RELEASE=moshcatty-0.1.0/0.1.1,
which produce packages that fail to start on Netcatty's Linux glibc floors.
Validate the minimum tag in resolve and fetch, skip pre-0.1.2 when picking
latest, and cover the reject path in unit tests.

* fix(mosh): pin MoshCatty owner and reject floor prereleases

Codex review vs main (P2):
- Always default MOSH_BIN owner/repo to binaricat/MoshCatty; do not
  inherit fork owner from GITHUB_REPOSITORY in resolve or fetch.
- Treat moshcatty-X.Y.Z-rcN as below final X.Y.Z so pins like
  moshcatty-0.1.2-rc1 cannot bypass the glibc floor.

* fix(mosh): accept build metadata in MoshCatty release tags

TAG_RE rejected '+' so moshcatty-0.1.2+build.1 failed validation even
though the version parser and isAtLeastMinRelease accepted it. Align
the regex and require a successful semver parse.

scripts/github-workflow-build.test.cjs

@@ -7,8 +7,6 @@ const buildWorkflow = fs.readFileSync(
   path.join(__dirname, "..", ".github", "workflows", "build.yml"),
   "utf8",
 );
-const moshLinuxScript = fs.readFileSync(path.join(__dirname, "build-mosh", "build-linux.sh"), "utf8");
-const moshMacScript = fs.readFileSync(path.join(__dirname, "build-mosh", "build-macos.sh"), "utf8");
 const etLinuxScript = fs.readFileSync(path.join(__dirname, "build-et", "build-linux.sh"), "utf8");
 const etMacScript = fs.readFileSync(path.join(__dirname, "build-et", "build-macos.sh"), "utf8");
 
@@ -134,17 +132,6 @@ test("build workflow builds Linux x64 native modules in a glibc 2.28 container",
   );
 });
 
-test("mosh binary build scripts retry source downloads before failing CI", () => {
-  for (const [name, script] of [
-    ["linux", moshLinuxScript],
-    ["macos", moshMacScript],
-  ]) {
-    assert.match(script, /curl_retry\(\)/, `${name} mosh build must use retrying downloads`);
-    assert.match(script, /--retry 8/, `${name} mosh build must retry transient HTTP failures`);
-    assert.match(script, /--retry-max-time 600/, `${name} mosh build must bound retry time`);
-  }
-});
-
 test("et binary build scripts retry dependency configure and pin ninja", () => {
   for (const [name, script] of [
     ["linux", etLinuxScript],