https: honor per-request TLS options over agent options

[axedos]

Per-request TLS options passed to https.request() / https.get() are silently
ignored when the https.Agent in use was constructed with the same option.
http.Agent merges the request options over the agent's own options, letting
the agent's value win.

That is surprising and can weaken security for TLS options in particular: a
per-request rejectUnauthorized: true on an agent configured with
rejectUnauthorized: false still sends the request with certificate
verification disabled. The same applies to ca and servername.

CVE-2026-58040 already handled this for checkServerIdentity by tagging the
request so the socket is not reused. This change generalizes that approach:

when a per-request rejectUnauthorized, ca, or servername differs from the
agent's value, request() captures the override and createConnection()
re-applies it, and the socket is not reused.

Refs: 52a8ace880d

[nodejs-github-bot]

Review requested:

• @nodejs/crypto
• @nodejs/http
• @nodejs/net

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.35%. Comparing base (bc6e1ad) to head (7145186).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66288      +/-   ##
==========================================
- Coverage   90.37%   90.35%   -0.02%     
==========================================
  Files         790      790              
  Lines      273807   273850      +43     
  Branches    52367    52389      +22     
==========================================
- Hits       247446   247441       -5     
- Misses      16869    16918      +49     
+ Partials     9492     9491       -1     

Files with missing lines	Coverage Δ
lib/https.js	98.11% <100.00%> (+0.90%)	⬆️

... and 36 files with indirect coverage changes

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