feat(claude): add fish-validate and lua-format skills

Add fish-validate skill for syntax checking and formatting .fish files,
lua-format skill for stylua formatting, and fish_indent PostToolUse hook.

.claude/settings.json

@@ -18,6 +18,10 @@
           {
             "type": "command",
             "command": "fp=$(cat | jq -r '.tool_input.file_path // empty') && [ -n \"$fp\" ] && [ -f \"$fp\" ] && case \"$fp\" in *.sh|*/bin/*) head -1 \"$fp\" | grep -qE '^#!.*(ba)?sh' && command -v shfmt > /dev/null && shfmt -i 2 -bn -ci -sr -fn -w \"$fp\";; esac; exit 0"
+          },
+          {
+            "type": "command",
+            "command": "fp=$(cat | jq -r '.tool_input.file_path // empty') && [ -n \"$fp\" ] && [ -f \"$fp\" ] && case \"$fp\" in *.fish) command -v fish_indent > /dev/null && fish_indent -w \"$fp\";; esac; exit 0"
           }
         ]
       }

.claude/skills/fish-validate/SKILL.md

@@ -0,0 +1,38 @@
+---
+name: fish-validate
+description: >-
+  Validate fish scripts after editing.
+  Apply when writing or modifying any .fish file
+  in config/fish/.
+user-invocable: false
+allowed-tools: Bash, Read
+---
+
+After editing any `.fish` file in `config/fish/`, validate it:
+
+## 1. Syntax check
+
+```bash
+fish --no-execute <file>
+```
+
+If syntax check fails, fix the issue before proceeding.
+
+## 2. Format check
+
+Run `fish_indent` to verify formatting:
+
+```bash
+fish_indent --check <file>
+```
+
+If formatting differs, apply it:
+
+```bash
+fish_indent -w <file>
+```
+
+## Key files to never validate
+
+- Files inside `config/fish/functions/` prefixed with `_tide_`
+  (managed by the tide prompt plugin)

.claude/skills/lua-format/SKILL.md

@@ -0,0 +1,22 @@
+---
+name: lua-format
+description: >-
+  Format Lua files after editing.
+  Apply when writing or modifying any .lua file.
+user-invocable: false
+allowed-tools: Bash
+---
+
+After editing any `.lua` file, format it with stylua:
+
+```bash
+stylua <file>
+```
+
+Project settings are in `stylua.toml` (90-char line length).
+
+If stylua is not available, skip formatting silently.
+
+## Files to never format
+
+- Files inside `config/nvim/` managed by plugins (lazy.nvim lockfile)