system/nxpkg: Validate catalog and database contents before use.

[aviralgarg05]

Note: Please adhere to Contributing Guidelines.

Depends-On: /pull/3642

Summary

A manifest read from a catalog, and an entry read from the installed
database, were used as they arrived. A name or a version containing a path
separator therefore reached the filesystem, and a database could name a
current version that it did not list among the installed ones.

This checks those fields are usable as a single path component, that the
current and previous versions appear in the recorded version list, and
applies a size limit to each field.

Version comparison also had two problems: it could overflow on a long
numeric prefix, and it treated versions sharing that prefix as equal, so 1a
and 1b compared the same. It now compares the numeric part without
overflowing and falls back to the remainder.

The manifest gains an optional icon, and the manifest actually recorded for
an installed version can now be read back, which matters after a rollback
has left the installed version behind the catalog.

This is the second of four parts of #3642, which was one commit covering
several unrelated changes.

Impact

• New feature: NO, this is validation and correctness on existing paths.
• User adaptation: NO.
• Build: NO.
• Hardware: NO.
• Documentation: NO.
• Security: YES. A catalog or database that has been tampered with can no
  longer smuggle a path traversal through a name or version field.
• Compatibility: A manifest whose fields were already valid parses as
  before. One that was not is now rejected instead of being acted on.

Testing

Build host: macOS 26.5, arm64, xtensa-esp-elf-gcc 14.2.0
(esp-14.2.0_20251107).

Target: Xtensa / ESP32-S3, Waveshare ESP32-S3-Touch-LCD-7.

• nxstyle, tools/checkpatch.sh, codespell and git diff --check on
  every changed file
• all system/nxpkg sources compiled for the target with this commit
  applied on top of system/nxpkg: Make the storage root configurable and crash-safe. #3642

This commit does not build on master alone because it uses declarations
added by #3642; the Depends-On line above lets CI apply that first.

PR verification Self-Check

• This PR introduces one focused change.
• I have updated all required description fields above.
• I have reviewed and signed every commit.
• This PR adheres to the current contribution and coding guidelines.
• My PR is still work in progress.
• My PR is ready for review and can be safely merged.

[github-actions]

🔗 Cross-repo PR dependencies

The read-only Build run reported the following dependent PR(s) and fetched head SHA(s):

• system/nxpkg: Make the storage root configurable and crash-safe. #3642 @ ca37b4d

CI run: https://github.com/apache/nuttx-apps/actions/runs/31526606011