fix(push-guard): single reader, whole-word dir tokens, payload fallback, bad-value banner

Run D2 of manual-push mode (BDR-114).

- push-guard sources lib/gitflow.sh once (absolute path) and reads each
  candidate dir through gitflow_push_mode; a missing lib denies.
- Dir tokens are extracted as whole shell words: a fully quoted token
  (inner apostrophe allowed) is resolved, a backslash-escaped space is
  unescaped deterministically, a token mixing quoted and unquoted parts
  is refused (fail closed) instead of resolving to its parent.
- A payload jq cannot parse is scanned as raw text with its JSON escapes
  folded; a push-looking one gets the static deny through the trap.
- The 20-token cap runs before any per-token classification (a flood of
  20 000 tokens is refused in 0.13 s; T58 locks it under 5 s).
- `case "$mode"` has a deny default; missing core tools warn and allow.
- T42 compares the deny list against main (the last release) instead of
  HEAD; literal-true, mixed-token, broken-payload, lib-missing and
  banner-on-bad-value cases added (98 checks).
- session-start banner reads the mode through the verb and shows
  `push : manual (autopush bad)` on an unparseable value.
- tour hints quote "<abs project>".

hooks/session-start.sh

@@ -53,7 +53,6 @@ _gf_lib="$(dirname "${BASH_SOURCE[0]}")/../lib/gitflow.sh"
 if [ -f "$_gf_lib" ] && git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
   GF_REFRESHED=$(bash "$_gf_lib" reconcile-hooks 2>/dev/null | sed -n 's/^gitflow hooks refreshed: *//p')
 fi
-unset _gf_lib
 
 # ── graphify threshold signal (BDR-097) ──
 # Informs, never acts: one banner line when the repo holds ≥ 200 tracked code
@@ -232,9 +231,12 @@ if [ -n "$GF_REFRESHED" ]; then
 fi
 # ── manual-push mode (BDR-111): one lock line when this repo never auto-pushes ──
 # %-46s, not 44: bash printf pads by BYTES and "—" is 3 bytes (2 extra).
-if [ "$(git config --bool --default true gitflow.autopush 2>/dev/null)" = false ]; then
-  printf "│  🔒 %-46s│\n" "push : manual (autopush=false) — ! git push"
-fi
+_pm=$( [ -r "$_gf_lib" ] && bash "$_gf_lib" push-mode 2>/dev/null )
+case "$_pm" in
+  manual) printf "│  🔒 %-46s│\n" "push : manual (autopush=false) — ! git push" ;;
+  invalid) printf "│  🔒 %-46s│\n" "push : manual (autopush bad) — ! git push" ;;
+esac
+unset _pm _gf_lib
 if [ -n "$GRAPHIFY_HINT" ]; then
   printf "│  🕸️  %-44s│\n" "${GRAPHIFY_HINT:0:44}"
   printf "│             %-40s│\n" "→ /graphify (AST, seconds) — you decide"