feat: add vite_allowed_hosts config option for Vite dev server

[milochen0418]

Add a configurable vite_allowed_hosts field to rx.Config that controls whether allowedHosts: true is set in the Vite dev server configuration.

This allows users running Reflex in Docker, Codespaces, or behind a reverse proxy to opt-in to allowing all hosts, preventing 403 Forbidden errors from Vite's host header validation.

Default is False (original behavior, Vite only allows localhost). Users can enable it in rxconfig.py:
config = rx.Config(app_name="myapp", vite_allowed_hosts=True)
Or via environment variable:
REFLEX_VITE_ALLOWED_HOSTS=true reflex run

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• New feature (non-breaking change which adds functionality)

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[codspeed-hq]

Merging this PR will degrade performance by 3.03%

❌ 1 regressed benchmark
✅ 7 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	test_compile_stateful[_stateful_page]	150.8 µs	155.5 µs	-3.03%

---

_{Comparing milochen0418:feat/vite-allowed-hosts-config (5170c6f) with main (e7c3742)}

[greptile-apps]

Greptile Summary

This PR adds a new vite_allowed_hosts configuration option to allow users to opt-in to permitting all hosts in the Vite dev server, addressing 403 errors in containerized environments (Docker, Codespaces, reverse proxies).

Key changes:

• Added vite_allowed_hosts: bool field to rx.Config (defaults to False for backward compatibility)
• Modified vite config template to conditionally insert allowedHosts: true in server configuration
• Environment variable support via REFLEX_VITE_ALLOWED_HOSTS works automatically through existing config loading

Implementation quality:
The code follows existing patterns and is well-structured with proper documentation. However, there's a concern about whether allowedHosts is a valid Vite configuration option - Vite's official documentation doesn't list this server option (it's a webpack-dev-server feature). Consider verifying this works with the version of Vite being used.

Confidence Score: 3/5

• This PR is safe to merge with verification needed for the Vite configuration option
• The implementation is clean and follows existing patterns, but there's uncertainty about whether allowedHosts is a supported Vite server option. This needs verification to ensure the feature actually works as intended. No tests were added for this new configuration.
• reflex/compiler/templates.py needs verification that allowedHosts works with Vite

Important Files Changed

Filename	Overview
reflex/compiler/templates.py	Added allowed_hosts parameter to vite_config_template with conditional insertion of allowedHosts config
reflex/config.py	Added vite_allowed_hosts boolean field to BaseConfig with proper documentation
reflex/utils/frontend_skeleton.py	Passes config.vite_allowed_hosts to vite_config_template function

_{Last reviewed commit: 5170c6f}

[greptile-apps]

_{3 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[milochen0418]

Merging this PR will degrade performance by 3.03%

❌ 1 regressed benchmark ✅ 7 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

Benchmark BASE HEAD Efficiency
❌ test_compile_stateful[_stateful_page] 150.8 µs 155.5 µs -3.03%
Comparing milochen0418:feat/vite-allowed-hosts-config (5170c6f) with main (e7c3742)

The 3.03% regression in test_compile_stateful (5µs difference) is within measurement noise and unrelated to this change — we only added a default False parameter and a conditional string line.