docs: repair links left dangling by the operations-doc removal

Untracking the ops docs broke every reference to them. Repoints or removes
those references across README, architecture, ROADMAP, the archive index,
lifecycle TESTING, the hardening plan, and the security docs — pointing at
the issue tracker where a live task list was meant, and dropping the entry
entirely where it only existed to link an internal file.

Also fixes two pre-existing broken links found by validating every relative
link in the tracked docs:
- README linked docs/OPEN_SOURCE_READINESS.md, which never existed
  (underscores vs hyphens).
- reticulum-daemon/README.md linked a local Claude session plan at
  ../../.claude/plans/enchanted-strolling-rocket.md — outside the repo, and
  a path that would have shipped publicly pointing at nothing.

All relative links in tracked markdown now resolve: 0 broken.
audit-secrets.sh still 5/5.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/security/PSBT-SIGNING-ARCHITECTURE.md

@@ -23,7 +23,7 @@
 > - **§5 (LND) is unaffected and remains accurate**, including **§5.4's honesty table**, which is
 >   correct as written and unchanged.
 >
-> **For the current state, read `docs/security/KEY-03-SIGNING-POSTURE.md`** — it records the
+> **Note:** the current signing-posture record is maintained internally. It records the
 > deletion with its evidence, an honest per-step coverage map of the LND PSBT round trip, and the
 > verdict on whether an external signer can sign a default node's PSBT today (it cannot: no fleet
 > node is provisioned watch-only). Phases 2-7 below are unaffected as design targets.