Optimize PHP INI defaults for embedded environment

[devin-ai-integration]

Summary

Two changes to the embeded_ini_defaults function in embeder.cpp:

1. Replace deprecated iconv.internal_encoding with default_charset
iconv.internal_encoding has been deprecated since PHP 5.6 and triggers deprecation notices on PHP 8.x. The modern replacement is default_charset, which serves as the encoding default for iconv, mbstring, htmlspecialchars, and htmlentities. Value remains UTF-8.

2. Change memory_limit from 3072M to -1 (unlimited)
   For an embedded SAPI there is no multi-tenant server environment where a per-request memory limit protects against resource exhaustion. -1 lets the OS enforce actual memory limits instead of an arbitrary 3GB ceiling.

The memory_limit and zlib.output_compression entries were reordered as a side effect; no other settings were modified.

Review & Testing Checklist for Human

• Verify memory_limit = -1 is acceptable for your use case. If the embedded PHP environment ever runs untrusted or poorly-written scripts, removing the memory ceiling means a runaway script could consume all system memory until the OS kills the process. If a safety net is desired, consider a higher-but-finite value instead.
• Confirm broadening from iconv.internal_encoding to default_charset is desired. default_charset has a wider scope—it also affects htmlspecialchars, htmlentities, and mbstring, not just iconv. In practice PHP 8.x already defaults default_charset to UTF-8, so the net effect should be zero, but verify no downstream code relies on default_charset being unset by the embedder.
• Build and smoke-test on Windows with Visual Studio — this project cannot be compiled on Linux, so no build verification was performed.

Notes

• zlib.output_compression = 0 was kept even though it is redundant (already the PHP default and irrelevant for embed SAPI which doesn't serve HTTP). Removing it is optional cleanup.
• com.allow_dcom = 1 was reviewed but left as-is; note that it enables remote/distributed COM object instantiation, which has security implications if not needed.
• phar.readonly = 0 was reviewed but left as-is; PHP docs recommend keeping it enabled on production machines.

Link to Devin session: https://app.devin.ai/sessions/5cc20d5ba3324bb3ba32c56d76986af7
Requested by: @ZmotriN

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring