Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.env.example:
- Line 50: There is a duplicate environment variable definition for
WEBLATE_REGISTRATION_OPEN; remove the redundant entry so the variable is defined
only once (keep the intended value and delete the other line), ensuring the
single remaining WEBLATE_REGISTRATION_OPEN entry reflects the correct
boolean/value used by the application.

In `@src/boost_weblate/endpoint/serializers.py`:
- Around line 87-115: The _flatten_field_errors function in
AddOrUpdateRequestSerializer currently stringifies DRF ErrorDetail objects which
breaks stable error-code mapping; modify _flatten_field_errors to propagate each
error's drf_code (use getattr(err, "code", None)) and return tuples like
(subfield, message, drf_code) instead of just (subfield, message), update any
call sites (including _code_for_drf_error) to accept the new triplet shape, and
change _code_for_drf_error to map DRF codes directly (e.g., ListField codes
"not_a_list" and "empty" → INVALID_SUBMODULE_LIST, missing field "required" →
REQUIRED_FIELD) rather than doing substring matching on message text. Ensure
nested branches (lists, dicts, ErrorDetail instances) preserve and propagate the
drf_code and adjust tests/consumers to handle the new tuple form.

In `@src/boost_weblate/endpoint/services.py`:
- Around line 131-138: The code currently runs subprocess.run(...) and uses
git_status.stdout without checking git_status.returncode, so add an explicit
check after the subprocess call (inspect git_status.returncode) and treat any
non-zero return code as a failure: log the error including git_status.stderr and
git_status.returncode (using the existing logger), and abort/raise (do not
proceed with DB deletion) when returncode != 0; update the block around the
subprocess.run invocation and the git_status variable usage to enforce this
explicit failure path (reference: git_status, subprocess.run call that uses
["git", "-C", base_path, "status", "--porcelain"]).
- Around line 146-156: The git commit call in subprocess.run (the one building
args with "git", "-C", base_path, "commit", "-m", f"Remove translation files for
deleted component: {name}", "--author", author) is not path-scoped and may
include unrelated staged changes; change the command to explicitly limit the
commit to the removed translation file paths by appending "--" followed by the
list of removed file paths (e.g., a variable like removed_paths or
removed_files) to the args passed to subprocess.run so only those files are
committed (ensure you pass the exact relative paths as arguments after the
"--").