refactor(skills): keep style instructions local

src/skills/nix-style/SKILL.md

@@ -6,4 +6,29 @@ description: Use when creating, editing, or reviewing Nix files in this reposito
 # nix-style
 
 Use this skill as the source of truth for repository Nix conventions.
-Follow the shared style skill instructions in `src/skills/style-skill.md`.
+
+## Load rules
+
+Read every Markdown file directly under [`rules/`](rules/) before applying this skill.
+Resolve [`rules/`](rules/) relative to this `SKILL.md`.
+
+Finish when all discovered rule files have been read.
+
+## Apply rules
+
+Apply the loaded rules when editing or reviewing Nix files.
+When loaded rules conflict, follow the most specific rule.
+
+After editing Nix files, run:
+
+```bash
+nix run .#fix
+```
+
+Finish when `nix run .#fix` succeeds and the Nix change follows the loaded rules.
+If the command fails, report the failure.
+
+## Maintain rules
+
+When adding or changing files under [`rules/`](rules/), read [`RULE-FORMAT.md`](RULE-FORMAT.md) first.
+Finish when the changed rule files follow that format.

src/skills/rust-style/RULE-FORMAT.md

@@ -0,0 +1,17 @@
+# Rule format
+
+Use this structure for each rule:
+
+```md
+## Rule title
+
+### Rule
+
+State enforceable instructions.
+
+### Rationale
+
+Explain why the rule exists.
+```
+
+Add `### Examples` only when examples clarify the rule.

src/skills/rust-style/SKILL.md

@@ -6,4 +6,29 @@ description: Use when creating, editing, or reviewing Rust files in this reposit
 # rust-style
 
 Use this skill as the source of truth for repository Rust conventions.
-Follow the shared style skill instructions in `src/skills/style-skill.md`.
+
+## Load rules
+
+Read every Markdown file directly under [`rules/`](rules/) before applying this skill.
+Resolve [`rules/`](rules/) relative to this `SKILL.md`.
+
+Finish when all discovered rule files have been read.
+
+## Apply rules
+
+Apply the loaded rules when editing or reviewing Rust files.
+When loaded rules conflict, follow the most specific rule.
+
+After editing Rust files, run:
+
+```bash
+nix run .#fix
+```
+
+Finish when `nix run .#fix` succeeds and the Rust change follows the loaded rules.
+If the command fails, report the failure.
+
+## Maintain rules
+
+When adding or changing files under [`rules/`](rules/), read [`RULE-FORMAT.md`](RULE-FORMAT.md) first.
+Finish when the changed rule files follow that format.

src/skills/style-skill.md

@@ -1,29 +0,0 @@
-# Style skill instructions
-
-Use this document for skills that own repository style conventions.
-
-## Load rules
-
-Read every Markdown file directly under `rules/` before applying the skill.
-Resolve `rules/` relative to the skill's `SKILL.md`.
-
-Finish when all discovered rule files have been read.
-
-## Apply rules
-
-Apply the loaded rules when editing or reviewing files covered by the skill.
-When loaded rules conflict, follow the most specific rule.
-
-After editing files covered by the skill, run:
-
-```bash
-nix run .#fix
-```
-
-Finish when `nix run .#fix` succeeds and the change follows the loaded rules.
-If the command fails, report the failure.
-
-## Maintain rules
-
-When adding or changing files under `rules/`, read the shared rule format at `src/skills/RULE-FORMAT.md` first.
-Finish when the changed rule files follow that format.