add CLI flags for controlling file collection behavior during ipfs add:
- `--dereference-symlinks`: recursively resolve symlinks to their target
content (replaces deprecated --dereference-args which only worked on
CLI arguments). wired through go-ipfs-cmds to boxo's SerialFileOptions.
- `--empty-dirs` / `-E`: include empty directories (default: true)
- `--hidden` / `-H`: include hidden files (default: false)
these flags are CLI-only and not wired to Import.* config options because
go-ipfs-cmds library handles input file filtering before the directory
tree is passed to kubo. removed unused Import.UnixFSSymlinkMode config
option that was defined but never actually read by the CLI.
also:
- wire --trickle to Import.UnixFSDAGLayout config default
- update go-ipfs-cmds to v0.15.1-0.20260117043932-17687e216294
- add SYMLINK HANDLING section to ipfs add help text
- add CLI tests for all three flags
ref: https://github.com/ipfs/specs/pull/499
01b1ce0cca