chore(caveman): purge plugin + always-on integration

Disable + uninstall caveman@caveman and delete every repo dependency on
it: SessionStart/UserPromptSubmit hook blocks, standalone hook files,
settings.json enabledPlugins + marketplace entries, install-plugins.sh
STEP 5.5, update-all.sh refresh step, plugins.lock.json entry, doctor.sh
checks, lib/detect-plugins.sh helpers, lib/profile.sh + plugin-advisor +
skills/profile protected-list entries, .gitignore runtime-file block,
and README/USAGE docs. Dead /caveman:compress refs replaced with
manual/claude.ai guidance. Memory-registry terse-format convention kept
(separate subsystem). Version 3.4.0 -> 3.5.0.

On a subscription plan caveman's ~75% output-token compression has no
cost benefit, and the always-on hooks added friction on validation
gates and client deliverables.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01X3e8LaH2vymmxyh36h3jFU

CLAUDE.md

@@ -104,8 +104,8 @@ quoted exact, IDs (BDR/LRN/BLK/EVAL-XXX) + dates unchanged. Pattern:
 `[thing] [action] [reason]. [next step].` Rationale: registries load
 every session — caveman cuts ~40% input tokens, zero substance loss.
 Applies to direct writes AND skill CAPITALIZE steps (close, ship-feature,
-feat, bugfix, hotfix, commit-change). Existing entries: compress via
-`/caveman-compress <file>`.
+feat, bugfix, hotfix, commit-change). Legacy entries (pre-format-rule):
+compress manually or via claude.ai on demand.
 
 **Routing — what goes where:**
 - Choice with tradeoffs you'd defend → `decisions.md`.