Fix/dtvcc allocation panic

[pranavshar223]

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This PR removes panics from the CEA-708 decoder initialization path.

Previously, allocation failures for dtvcc_tv_screen or
dtvcc_service_decoder would cause a hard panic, crashing CCExtractor.

Instead, allocation failures are now handled gracefully by logging
a debug message and disabling the affected service decoder while
allowing processing to continue.

This improves robustness and aligns Rust behavior with the legacy C
implementation.

[cfsmp3]

Thanks for working on improving the robustness of the CEA-708 decoder initialization!

The concept is good - handling allocation failures gracefully instead of panicking. However, there are several issues that need to be fixed before this can be merged:

1. CRLF Line Endings Breaking Linux Builds

All files in this PR have Windows-style CRLF line endings instead of Unix LF:

decoder/mod.rs: ASCII text, with CRLF line terminators
pre-build.sh: ASCII text, with CRLF line terminators

This breaks the Linux build - shell scripts with CRLF don't work on Unix systems. This is why the CI is failing:

• build_shell - FAILURE
• build_autoconf - FAILURE
• format_rust - FAILURE

Fix: Configure your git to handle line endings properly:

git config --global core.autocrlf input

Then convert the files:

dos2unix src/rust/src/decoder/mod.rs linux/pre-build.sh

Or rebase your branch on a fresh master checkout.

2. Unrelated Changes from PR #2045

This PR includes changes from #2045 (userdata.rs documentation and debug logging). These should be in a separate PR - #2045 is already pending review.

Please remove src/rust/src/es/userdata.rs from this PR.

3. Messy Commit History

The commits include "retry the test" and "restore all changes" which don't describe the actual changes. Consider squashing into a clean commit with a descriptive message.

4. Minor: Trailing Whitespace

                    continue;
                }       // <-- extra spaces here

The Actual Fix Looks Good

Once the above issues are fixed, the core change is reasonable:

// Before: panic on allocation failure
panic!("Failed to allocate dtvcc_tv_screen");

// After: log and gracefully skip the service
debug!(msg_type = DebugMessageFlag::DECODER_708;
    "DTVCC: Failed to allocate tv_screen for service {}, disabling service", i + 1);
continue;

The cleanup of the already-allocated tv_screen when decoder allocation fails is also correct:

unsafe {
    std::alloc::dealloc(tv_ptr as *mut u8, tv_layout);
}

Summary

Please:

1. Fix line endings (dos2unix or fresh checkout)
2. Remove userdata.rs changes (belongs in #2045)
3. Squash commits into clean history
4. Push updated branch

Looking forward to the updated PR!