docs(functions): merge remaining manual-only facts into headers

Word-level diff of every manual entry against its generated counterpart
surfaced 546 tokens present in the manual and absent from the header —
losses reconcile.py missed, because it compared description length and
these headers are longer overall thanks to ARGUMENTS/RETURNS.

Merged the substantive ones (546 -> 202 residual tokens, the remainder
being synonym drift). Notable real fixes:

- git-clean: -f/--force was missing from ARGUMENTS entirely
- pkg: per-package-manager query table
- qc: cli-role rationale, role paths, --role passthrough
- config-help: site URL, xdg-open, man page path, case-insensitivity
- agents-init: idempotency, .gitignore paths, upstream pull, wrapper callers
- smart_exit: exit-builtin wiring note, $SCROLLBACK_HISTORY_DIR

The manual's claim that claude/agy pass `agents-init --agents` is stale;
both pass `--quiet` (full setup). Header wins, manual dropped.

functions/ssh.fish

@@ -9,7 +9,8 @@
 #
 # DESCRIPTION
 #   Wraps ssh with kitten ssh inside Kitty terminal for better terminal
-#   integration (e.g. terminfo forwarding). Falls back to system ssh on
+#   integration (terminfo forwarding, multiplexing, copy/paste support).
+#   Falls back to system ssh on
 #   other terminals.
 #
 # ARGUMENTS