Fix nested TypeForm alias evaluation

[Rich Chiodo (rchiodo)]

Summary

• consult the TypeForm-specific cache for nested generic arguments evaluated in a TypeForm context
• preserve incomplete-cache generation checks when selecting cached results
• add regression coverage for PEP 695 aliases used as bounded generic arguments

Fixes #11633

Testing

• npx jest typeEvaluator8.test --forceExit -t "TypeForm"
• npm run build (packages/pyright-internal)

[Heejae Chang (heejaechang)]

🔒 Automated review in progress — Heejae Chang (@heejaechang) is auto-reviewing this PR.

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[Heejae Chang (heejaechang)]

A runtime-first evaluation can still reuse the ordinary cache for nested TypeForm arguments, restoring the invalid TypeAliasType diagnostic. This needs a context-specific cache lookup and regression coverage.

[Rich Chiodo (rchiodo)]

Fixed in f274ace — TypeForm argument evaluation now consults only the context-specific TypeForm cache and reevaluates when that entry is missing, so an ordinary runtime-cache hit cannot short-circuit contextual validation. Runtime-first regression coverage includes nested class aliases, generic aliases, ParamSpec, and TypeVarTuple cases.

[Heejae Chang (heejaechang)]

Approved via Review Center.