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

skills/profile/SKILL.md

@@ -56,7 +56,7 @@ lists items + types:
 | `mcp` (other)           | advisory — prints manual `claude mcp add …` command |
 | `cli`                   | advisory only — reports installed/not-installed |
 
-**Always-on plugins** (`caveman`, `security-guidance`, `superpowers`) are
+**Always-on plugins** (`security-guidance`, `superpowers`) are
 protected — `set` will refuse to disable them even if the profile omits them.
 **Managed plugins** that `set` may disable when not in profile:
 `ui-ux-pro-max@ui-ux-pro-max-skill`, `plugin-dev@claude-code-plugins`,