fix(ci): silence CI/tool noise found auditing the test-job log

An audit of a full green run's test + build-docs logs (agy scan, spot-
checked) turned up stray output beyond the mkrep git-init hint already
fixed. Two real bugs, plus CI-config cosmetics:

- agents-vault.fish/agents-init.fish: `set -l x (some_fish_function ...)`
  command substitutions do not inherit a caller-scoped stderr redirect in
  fish (proven with a two-line repro: `outer 2>/dev/null` where outer
  does `set -l x (inner)` still leaks inner's stderr to the real
  terminal). This let _agents_repo_ensure_symlink's and
  _agents_repo_sync's raw internal error messages leak past `--silent`
  for real users too, always duplicating the clean summary message each
  caller already echoes on failure. Fixed at all 4 call sites by adding
  an explicit `2>/dev/null` directly on each command substitution, since
  a redirect on the outer call cannot reach it.
- ci.yml: apt-get install missing `apt-utils`, so debconf printed
  "delaying package configuration" on every install in both jobs --
  installing it first fixes the chicken-and-egg.
- ci.yml: added `NODE_OPTIONS: --no-deprecation` at the build-docs job
  level to silence Node's internal punycode-module deprecation notice
  (astro's toolchain still pulls it in transitively).
- ci.yml: `npm ci --no-fund` drops the funding nag.
- ci.yml: `gpg --batch --quiet --import` drops gpg's normal-case import
  status lines during the bot commit-signing setup.

Deliberately NOT silenced: npm's deprecated-glob warning, its audit
vulnerability summary, and its allow-scripts notice about esbuild's
postinstall -- these are genuine dependency-hygiene signal, not noise,
and no workflow-level flag exists to hide them without also hiding real
future findings. Also not fixable here: a Gitea Actions/act runner
warning ('runs-on' key not defined in CI/test) that traces to neither
workflow YAML in this repo -- both already set runs-on on every job,
confirmed twice; it's runner-internal, like actions/checkout's own
git-init hint in its Checkout-step preamble.

Verified: full suite 730/730 passing ($status 0); the exact mkdir-
collision repro that surfaced the command-substitution bug re-run
clean (rc=1, empty stderr); test-agents-vault.fish standalone,
320/320, zero occurrences of the previously-leaked messages.

functions/agents-init.fish

@@ -482,7 +482,11 @@ function agents-init --description 'scaffold AGENTS/ sub-repo with agent spec fi
     # a hook-rejected commit fell straight through to a reported success.
     set -l msg "chore: sync AGENTS repository"
     test $did_init -eq 1; and set msg "chore: initialize AGENTS repository"
-    set -l sync_out (_agents_repo_sync "$agents_dir" "$msg")
+    # 2>/dev/null: a command substitution's stderr does not inherit a
+    # caller-scoped redirect on this call (fish quirk), so _agents_repo_sync's
+    # own error message leaks past --silent regardless; it is redundant with
+    # the $sync_rc-driven echoes just below anyway.
+    set -l sync_out (_agents_repo_sync "$agents_dir" "$msg" 2>/dev/null)
     set -l sync_rc $status
     set -l failed 0
     if test $sync_rc -eq 2