chore: migrate timeflies-beam example to Fable.Beam rc.30 typed Cowboy API

[dbrattli]

Summary

Migrates the timeflies-beam example to Fable.Beam 5.0.0-rc.30 (Cowboy 5.0.0-rc.24) and removes every inline [<Emit>] Cowboy/Beam workaround in favour of the typed bindings.

The main Fable.Actor library is unchanged — its Fable.Beam reference is a floating 5.0.0-rc.* wildcard that already resolves to rc.30, and it uses no Cowboy/changed APIs.

Changes

Timeflies.fsproj

• Fable.Beam 5.0.0-rc.29 → 5.0.0-rc.30; Fable.Beam.Cowboy stays at 5.0.0-rc.24 (latest).

App.fs

• Delete the local route / hostRule / protoOpts / transportOpts [<Emit>] helpers.
• Use CowboyRouter.wildcard/route/hostRule/compile and Cowboy.tcpPort/protocolOpts/startClear.
• Switch the now-internal application.ensure_all_started to Application.ensureAllStarted.

Http.fs

• Replace the content-type header [<Emit>] with Maps.ofList — the helper added upstream in Fable.Beam#105 after this migration surfaced the gap (the array-based from_list lowered to a process-dictionary ref; ofList emits a direct maps:from_list([...])).
• Type init's return as HandlerResult<'State> since CowboyHandler.ok is now typed.

The example F# is now free of Cowboy/Beam Emits; the only remaining [<Emit>]s in the repo are Fable.Actor's own wire protocol in Platform.fs (fable_actor_msg / fable_actor_reply / EXIT), which are app-specific, not a Fable.Beam gap.

Verification

• dotnet build (lib type-check) ✓
• Fable BEAM transpile + rebar3 compile ✓ — inspected generated app.erl/http.erl: cowboy_router:compile([{'_', […]}]), [{port,3000}], #{env => #{dispatch => …}}, and clean maps:from_list([{<<"content-type">>, <<"text/html">>}]) (no process-dict-ref wrapper).
• just test-native 21/21 ✓
• just test-beam 21/21 ✓
• dotnet fantomas clean

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