feat(server-ng): serve HTTPS on the REST listener

[hubcio]

http.tls.enabled was read but never acted on: the REST listener
always bound plaintext, so bearer tokens and passwords crossed
the wire in clear despite TLS being configured.

Terminate TLS with the compio-native rustls substrate the binary
transports already use, rather than pulling tokio via axum-server.
Handshakes run off the accept path behind a bounded channel so a
slow peer cannot stall accept. Connections are served through a
hand-rolled hyper-util auto loop over HyperStream::new_tls;
cyper_axum::serve only wraps plaintext streams, and splitting the
TLS stream deadlocks full-duplex HTTP on compio's BiLock. ALPN
advertises h2 and http/1.1 for parity with the legacy server.
Credential errors surface as ListenerCredentials instead of a
panic, and enabling TLS with an empty cert_file or key_file now
fails config validation at boot.

An integration test spawns iggy-server-ng with http.tls enabled
and asserts /ping and /users/login return 200 over HTTP/2,
proving certificate loading, the handshake pump, and ALPN end to
end. reqwest's http2 feature is now pinned instead of enabled
transitively via testcontainers.

[codecov]

Codecov Report

❌ Patch coverage is 27.89116% with 106 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.82%. Comparing base (c42eca7) to head (4f84bcc).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
core/server-ng/src/http/tls.rs	17.75%	88 Missing ⚠️
core/server-ng/src/http.rs	0.00%	18 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master    #3672       +/-   ##
=============================================
- Coverage     73.60%   58.82%   -14.79%     
  Complexity      937      937               
=============================================
  Files          1297     1296        -1     
  Lines        143769   131701    -12068     
  Branches     119329   107334    -11995     
=============================================
- Hits         105822    77469    -28353     
- Misses        34582    50800    +16218     
- Partials       3365     3432       +67     

Components	Coverage Δ
Rust Core	55.61% <27.89%> (-18.24%)	⬇️
Java SDK	62.44% <ø> (ø)
C# SDK	71.04% <ø> (-1.16%)	⬇️
Python SDK	92.17% <ø> (ø)
PHP SDK	84.29% <ø> (ø)
Node SDK	91.22% <ø> (-0.13%)	⬇️
Go SDK	42.71% <ø> (+0.43%)	⬆️

Files with missing lines	Coverage Δ
core/configs/src/server_ng_config/validators.rs	52.89% <100.00%> (+10.46%)	⬆️
core/server-ng/src/http.rs	53.93% <0.00%> (-1.35%)	⬇️
core/server-ng/src/http/tls.rs	17.75% <17.75%> (ø)

... and 263 files with indirect coverage changes

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