Add project tag categorization and devserver port pre-allocation

Summary

• Projects can now be categorized with free-form tags. The Projects
  page shows a filter chip row (all / / untagged with counts),
  tag chips on each project row that toggle the filter when clicked,
  and a tag editor (chip-style input) reachable from each row and
  from the New Project modal at creation time.
• Tags are persisted under projects.projectTags in config.json
  and exposed via a new SetProjectTags Wails binding. Deleting a
  project also clears its tag entry. Mirrors the existing SSH host
  tag UX.
• Extracted FilterChip and the addTag / commitDraft helpers
  into shared modules so the SSH page and modal reuse them.
• Dev server now pre-allocates a free TCP port (3000+) and exports
  PORT / BROWSER=none to the child process, so multiple JS dev
  servers no longer collide on a single default port. The port read
  from log output still wins if the framework picks a different one.