fix: allow resolving context-dot for async functions

[christoph-dfinity]

By hardcoding the scope to None before, we made it so async functions would never be resolved for context-dot.

Threading the scope through fixes that.

Reported by @timohanke

@Kamirus I didn't see an obvious way to get a hold of a scope for the context dot suggestions in the LSP, so for now completions for async functions won't appear.

[caffeine-ci-bot]

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[github-actions]

Cursor AI review

👍 APPROVE — looks safe to merge

Category	Assessment	Details
Summary	✅	Threads scope_of_env into context-dot matching so async-returning self methods can resolve inside async scopes; adds a fail test and changelog entry.
Code Quality	✅	Reuses existing scope_of_env / Bi_match.bi_match_subs path already used by infer_call_instantiation; no speculative helpers.
Consistency	✅	Matches the call-site pattern at typing.ml:3737; LSP suggestions still pass None as noted in the PR.
Correctness	✅	Traced bi_match_subs Scope handling (bi_match.ml:569–576), parser ensure_scope_bind for local async funcs, scope_of_env, and contextual_dot/infer_callee — prior None made Scope instantiation impossible; non-async contexts still get None and reject.
Tests	✅	New test/fail/contextual-dot-async.mo with matching .ok/.ret.ok pairs: async use accepted (no diagnostic), sync use still M0072.
Changelog	✅	User-visible entry under ## Unreleased with (#6085), above frozen ## 1.14.1.

Verdict

Decision: APPROVE
Risk: Low
Reason: Contained frontend bug fix that supplies the async scope bi_match_subs already requires for Scope-bound functions; rejection outside async scope is unchanged and covered by the new fail test.

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Generated for commit 90f9c95

[github-actions]

Comparing from 58c3239 to 90f9c95:
The produced WebAssembly code seems to be completely unchanged.
In terms of gas, no changes are observed in 5 tests.
In terms of size, no changes are observed in 5 tests.

[alexandru-uta]

thanks, looks good