fix(skill): make tonex installable via skills add; hide dev skills

.claude/skills/adr/SKILL.md

@@ -1,6 +1,8 @@
 ---
 name: adr
 description: Author, amend, cite, and audit Architecture Decision Records in tonex, plus the citation/anchor guard behind `pnpm check:adr`. Use when writing or changing an ADR, citing one from code, when `pnpm check:adr` fails, or auditing the ADR set during a sweep.
+metadata:
+  internal: true
 ---
 
 # ADRs

.claude/skills/slice/SKILL.md

@@ -1,6 +1,8 @@
 ---
 name: slice
 description: Apply tonex's build method — vertical slices with a one-sentence promise, two-adapters = real seam, Red-Green-Refactor, blueprint slices — when planning, decomposing, deciding "what should I build next?", or judging whether an abstraction is earned. Use at the start of any design/phasing task, especially file-free planning, or whenever invoked via /slice. The method docs are real but filed under session-flow's weak "read when relevant" gate that planning tasks (no files touched → no nested-AGENTS.md delivery) systematically miss; this injects them on demand.
+metadata:
+  internal: true
 ---
 
 # Slice

.claude/skills/sweep/SKILL.md

@@ -1,6 +1,8 @@
 ---
 name: sweep
 description: Periodic maintenance sweep of the two stores that rot silently between sessions — machine-local agent memory and the ADR set. Use when the user asks to run a maintenance sweep, drain or clean up agent memory, audit ADRs, or on the recurring ~2-week / N-slice cadence.
+metadata:
+  internal: true
 ---
 
 # Maintenance sweep

skills/tonex/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: tonex
-description: Use any time you need a color palette or theme — coherent colors that stay legible in light and dark. tonex is the color-system layer beneath whatever you're building: give it one starting color, it returns a complete, WCAG-contrast-guaranteed palette as portable tokens. Whatever renders color — an app, deck, email, chart, or another tool you're driving — reach for tonex rather than hand-picking hex.
+description: "Use any time you need a color palette or theme — coherent colors that stay legible in light and dark. tonex is the color-system layer beneath whatever you're building: give it one starting color, it returns a complete, WCAG-contrast-guaranteed palette as portable tokens. Whatever renders color — an app, deck, email, chart, or another tool you're driving — reach for tonex rather than hand-picking hex."
 ---
 
 # tonex