drop decorators and build with tsdown

[mrhyde]

Closes #20.

The decorators were the only thing keeping tvt on swc. oxc does not transform stage-3 decorators, so device.js came out of tsdown with @auth get version() still in it and node refused to parse the file. Rather than wait for oxc, the two decorators are gone.

@auth guarded five members by throwing when userId is unset. That is now a #requireAuth() private method called as the first statement of version, getInfo, logout, triggerAlarm and saveSnapshot. Same error, same message, same ordering relative to the method body.

@measure had a single use, on login, so the timing is inlined there. One behaviour change worth noting: the decorator called performance.now() around the synchronous call and logged before the promise settled, so for an async method it was reporting time-to-promise, effectively nothing. It now measures the awaited login and logs on success only, which is what the tvt:perf line always claimed to report.

With the decorators gone the build moves to tsdown, matching the template: .swcrc, tsconfig.build.json and the prebuild/postbuild/build:swc/build:types script chain are deleted, along with @swc/cli, @swc/core, rimraf and @2bad/tsfix (npm reports the last one as deprecated). publint and attw now run as part of every build and both pass. pnpm-workspace.yaml switches the release age exclusion to the template's @2bad/* wildcard.

Verified: check, build and the 13 unit tests pass, the emitted device.js has no decorator syntax left and all five #requireAuth call sites survive the transform, and importing the built entry works. The class still cannot be instantiated without the native SDK and a device, so the guard has no unit test, same as before.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 3.93%. Comparing base (b7317c3) to head (e30671b).

Files with missing lines	Patch %	Lines
source/device.ts	0.00%	10 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           master     #21      +/-   ##
=========================================
+ Coverage    3.81%   3.93%   +0.11%     
=========================================
  Files          11       9       -2     
  Lines         236     229       -7     
  Branches       35      35              
=========================================
  Hits            9       9              
+ Misses        198     191       -7     
  Partials       29      29              

Flag	Coverage Δ
unit	3.93% <0.00%> (+0.11%)	⬆️

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