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/agy.fish

@@ -11,7 +11,9 @@
 #   Wrapper for the agy Antigravity AI CLI that ensures the AGENTS/
 #   sub-repository is initialized and any agent-made changes are committed
 #   before launch. Delegates all scaffold and commit logic to agents-init
-#   (full setup). All arguments are forwarded verbatim to the real agy binary.
+#   --quiet (full setup), which ensures AGENTS/ is scaffolded and CLAUDE.md
+#   is symlinked to AGENTS/AGENTS.md in the current project. All arguments
+#   are forwarded verbatim to the real agy binary.
 #
 #   Opinionated component (C1): when disabled via __fish_config_op_aliases
 #   (or the __fish_config_opinionated master), the command is passed through