feat: add reversible thread inbox state operations

Author: gnapse

README.md

@@ -69,6 +69,11 @@ tw inbox --unread                  # unread threads only
 tw thread view <ref>               # view thread with comments
 tw thread view <ref> --comment 123 # view a specific comment
 tw thread reply <ref>              # reply to a thread
+tw thread done <ref>               # archive thread (mark as done)
+tw thread reopen <ref>             # reopen archived thread
+tw thread unread <ref>             # mark thread unread
+tw thread read <ref>               # mark thread read
+tw thread restore <ref> --unread   # reopen and mark unread
 tw conversation unread             # list unread conversations
 tw conversation view <ref>         # view conversation messages
 tw msg view <ref>                  # view a conversation message
@@ -83,6 +88,26 @@ References accept IDs (`123` or `id:123`), Twist URLs, or fuzzy names (for works
 
 Run `tw --help` or `tw <command> --help` for more options.
 
+## Inbox State Workflows
+
+Thread inbox-state commands support single refs and bulk refs:
+
+```bash
+tw thread reopen 123 456 --yes                    # bulk reopen
+tw thread restore 123 --unread --json             # reopen + unread with JSON output
+tw thread done 123 --dry-run                      # preview archive operation
+```
+
+Each mutation command supports:
+
+```bash
+--yes                # skip bulk confirmation
+--dry-run            # preview without changing state
+--json               # include before/after state per thread
+```
+
+Migration note: `tw thread done` is now reversible via `tw thread reopen`.
+
 ## Shell Completions
 
 Tab completion is available for bash, zsh, and fish: