feat(profile): partition skills/plugins/MCPs/CLIs by usage profile

Ship lib/profile.sh + 9 profiles in lib/profiles/. A profile is a
plain-text file listing items + types (gstack | personal | external |
plugin@<marketplace> | mcp | cli). `profile set <name>` enables the
listed items and disables the rest:

  - gstack/personal/external skills: symlink toggle skills/ ↔
    skills-disabled/ (gstack__<name> prefix to avoid collisions; no
    prefix for personal/external).
  - plugins typed `plugin@<marketplace>`: actually toggled via
    `claude plugin enable|disable <name>@<marketplace>`. Allowlist:
    MANAGED_PLUGINS = ui-ux-pro-max, plugin-dev, pr-review-toolkit.
    Denylist: PROTECTED_PLUGINS = caveman, security-guidance,
    superpowers (always-on, never disabled even if absent from a
    profile).
  - mcp magic: delegated to lib/toggle-external.sh which already
    handles the MAGIC_API_KEY env lookup. Other MCPs stay advisory.
  - cli (rtk, gsd, ctx7, graphify): status-only, never auto-installed.

Profiles shipped:
  web        public website work — frontend + content + light dev
  seo        SEO + GEO + W3C audit (search/AI indexability + a11y)
  web-full   production website end-to-end (web ∪ seo ∪ qa-only/canary)
  backend    backend / API / system dev — no design, no SEO
  design     visual QA, design systems, mockups, polish
  dev        daily code work — features, fixes, refactor, ship
  qa         site testing, perf, canary, validation
  audit      comprehensive audit — security + SEO + perf + health
  minimal    strip all gstack skills (quiet session)

Commands:
  profile list / show <name> / current / apply <name> / set <name> /
  reset / diff <a> <b>

`current` heuristic returns "full" when nothing is disabled, otherwise
picks the profile with the highest available-ratio (counts both
"enabled" and "installed" — the latter for CLIs). Tiebreaker: larger
profile total wins, so web-full beats web at a 100% tie.

`reset` re-enables every gstack skill but does NOT touch plugins —
the user re-enables a managed plugin manually or via `apply <profile>`.
This is documented in the trailing info line.

Integration:
  - skills/profile/SKILL.md — `/profile` slash command, lists profiles,
    documents the per-type mechanism, points at lib/profile.sh.
  - agents/plugin-advisor.md — DETECT phase calls `profile current`,
    OUTPUT adds a PROFILE line, and TOGGLING EXTERNAL TOOLS gains a
    "Skill profiles" section with a signal → profile recommendation
    table.
  - lib/toggle-external.sh — header pointer to profile.sh for fine-
    grained activation (toggle-external still owns whole-gstack and
    magic-MCP toggles).
  - Makefile — `make profile cmd="set <name>"`, profile-list,
    profile-current, profile-reset.

Tested end-to-end: `set web` enables ui-ux-pro-max + magic; `set seo`
disables ui-ux-pro-max; `set minimal` disables ui-ux-pro-max but
spares always-on plugins; `reset` restores all 64 skills; shellcheck
clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Makefile

@@ -1,4 +1,4 @@
-.PHONY: help install plugin link doctor update new-skill
+.PHONY: help install plugin link doctor update new-skill profile profile-list profile-current profile-reset
 
 help: ## Show available commands
 	@grep -E '^[a-zA-Z_-]+:.*##' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*## "}; {printf "  make %-14s %s\n", $$1, $$2}'
@@ -22,6 +22,18 @@ onboard: link ## Onboard an existing project (run from the project directory)
 	@echo "Open Claude Code in your project directory and run: /onboard"
 	@echo "Or with hints: /onboard Python FastAPI monorepo"
 
+profile: ## Run profile.sh (usage: make profile cmd="set design")
+	@bash lib/profile.sh $(cmd)
+
+profile-list: ## List skill profiles (design, dev, qa, audit, minimal)
+	@bash lib/profile.sh list
+
+profile-current: ## Detect which skill profile is currently active
+	@bash lib/profile.sh current
+
+profile-reset: ## Re-enable all gstack skills (undo any profile set)
+	@bash lib/profile.sh reset
+
 new-skill: ## Create a new skill scaffold (usage: make new-skill name=myskill)
 	@test -n "$(name)" || (echo "Usage: make new-skill name=myskill" && exit 1)
 	@mkdir -p agents skills/$(name)