Cover every reachable branch

[winebarrel]

Coverage goes from 93.1% to 99.0%, with tests only. codecov.yml's floor moves from 90% to 99% with no threshold slack. The implementation is untouched.

What the new tests reach

branch	how
Profiles() open error, config and credentials files	a path whose parent is a file, so the failure is not "does not exist"
list_profiles error result	same
wrapTool schema error	a tool whose InputSchema cannot be marshalled
discoverTools profile-listing error	same as above
tools/list failure	receiving middleware on the fake server rejects the method
a tool whose inputSchema is not an object	receiving middleware rewrites the result
pagination	fake server with ServerOptions{PageSize: 1} and two tools
a cancelled tool call	cancelled context, and the session must survive it
connectCtx with no base context	called directly
Run over stdio	actually run; under go test stdin is /dev/null, so the client is at EOF and Run returns after serving
the session race	a gate holds one connect open while a session for the same profile is published, so the loser's session is discarded deterministically
drainBody read error	a reader that always fails
GetBody on a bodyless request	called, and asserted to stay bodyless

Why 99% and not 100%

Three statements cannot be reached from a test:

• json.Marshal on map[string]any{"profiles": []string}
• json.Marshal on a map json.Unmarshal just produced -- JSON has no NaN or Inf, so the round trip cannot fail
• SignHTTP's error, whose only source in aws-sdk-go-v2 v1.43.4 is buildSignature -> HMAC, which does not fail

Dropping those checks to reach a round number would be worse than the number, and Codecov has no line-level ignore -- only paths. So the target is 99% with threshold: 0%: the real ceiling, gated exactly.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.38%. Comparing base (e7ccb58) to head (f84062e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #6      +/-   ##
==========================================
+ Coverage   91.12%   98.38%   +7.25%     
==========================================
  Files           5        5              
  Lines         372      372              
==========================================
+ Hits          339      366      +27     
+ Misses         19        3      -16     
+ Partials       14        3      -11     

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