* sentry_close: fix return value documentation

* sentry_shutdown: fix return value documentation

* docs: replace legacy sentry_string_free with sentry_free

* Update include/sentry.h

* docs: improve sentry_attachment_s struct documentation

Clarify that the struct represents a union of two attachment types:
- File attachments (path-based)
- Buffer attachments (in-memory)

Add inline comments to group fields by usage and explain the
difference between 'path' (filesystem path) and 'filename'
(envelope attachment name). This addresses confusion about
why both fields exist and when each is used.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: apply clang-format to attachment struct documentation

Fix code formatting to match project style guidelines.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* docs: clarify filename field can be NULL in attachment struct

Update inline comment to indicate that filename field can be NULL,
in which case the basename of path is used as the attachment name.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

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Co-authored-by: Claude <noreply@anthropic.com>

#skip-changelog