feat(ctx7): coverage extension — fast-libs single source + reminder hook + executor briefs (BDR-078)

- lib/fast-libs.sh: detect/cache-status verbs, JS+Python manifests,
  7-day cache freshness, LC_ALL=C sort — replaces 3 hardcoded lists
  (ship-feature 0c, init-project 5c, onboard 3.5)
- hooks/ctx7-reminder.sh: once-per-session UserPromptSubmit nudge when
  the project carries fast-libs and .ctx7-cache/ is missing/stale
- find-docs: before-writing-code trigger + cache-first rule; dist is
  machine-owned (gitignored) so the durable patch lives in
  install-plugins.sh STEP ctx7 (idempotent, grep-guarded)
- feater/bugfixer briefs: fast-lib docs rule (fresh cache read, else
  2-topic ctx7 fetch, else NOTES cache miss + proceed)
- tests: lib/tests/fast-libs.test.sh (11 checks); shellcheck + full
  make test green (review-guards 5/0)

settings.json

@@ -281,6 +281,12 @@
             "command": "bash ~/.claude/hooks/design-toolchain-reminder.sh",
             "timeout": 5,
             "statusMessage": "Checking design signals..."
+          },
+          {
+            "type": "command",
+            "command": "bash ~/.claude/hooks/ctx7-reminder.sh",
+            "timeout": 5,
+            "statusMessage": "Checking fast-libs..."
           }
         ]
       }