feat(claude): add scaffolding and validation skills

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

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+---
+name: dotbot-validate
+description: >-
+  Validate Dotbot install.conf.yaml files after editing.
+  Apply when writing or modifying any install.conf.yaml.
+user-invocable: false
+allowed-tools: Bash, Read
+---
+
+After editing any `install.conf.yaml` file, validate it:
+
+## 1. YAML syntax
+
+```bash
+yamllint -d relaxed <file>
+```
+
+If yamllint is not available, fall back to:
+
+```bash
+python3 -c "import yaml; yaml.safe_load(open('<file>'))"
+```
+
+## 2. Link target verification
+
+For each `link` entry, verify the source path exists relative
+to the repo root. Report any missing source files.
+
+## 3. Host-specific configs
+
+Files in `hosts/<hostname>/install.conf.yaml` overlay the
+global config. Verify that any `include` directives reference
+existing files.
+
+## Key locations
+
+- `install.conf.yaml` — global config
+- `hosts/*/install.conf.yaml` — per-host overlays

.claude/skills/host-override/SKILL.md

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+---
+name: host-override
+description: >-
+  Create or extend host-specific config overlays
+  in hosts/<hostname>/ for machine-specific settings.
+user-invocable: true
+allowed-tools: Bash, Read, Write, Edit
+---
+
+When creating host-specific configuration overrides:
+
+## 1. Determine hostname
+
+```bash
+hostname -s
+```
+
+## 2. Directory structure
+
+Host overrides live in `hosts/<hostname>/` mirroring the
+global layout:
+
+```
+hosts/<hostname>/
+  base/           -> ~/.*
+  config/         -> ~/.config/
+  install.conf.yaml
+```
+
+## 3. Create install.conf.yaml
+
+If it doesn't exist, create `hosts/<hostname>/install.conf.yaml`
+following the Dotbot format. Use `include` to layer on top of
+the global config:
+
+```yaml
+- defaults:
+    link:
+      create: true
+      relink: true
+      force: true
+```
+
+## 4. Git config overrides
+
+The most common override is `hosts/<hostname>/config/git/overrides/config`.
+This is where host-specific git user, signing keys, and credential
+helpers go. Always `[include]` the shared config:
+
+```ini
+[include]
+  path = ~/.dotfiles/config/git/shared
+```
+
+## 5. Test
+
+Run `./install` to apply. Dotbot processes
+`hosts/<hostname>/install.conf.yaml` after the global config.

.claude/skills/new-fish-function/SKILL.md

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+---
+name: new-fish-function
+description: >-
+  Scaffold a new fish function in config/fish/functions/
+  with proper conventions and event handling.
+user-invocable: true
+allowed-tools: Bash, Read, Write, Edit
+---
+
+When creating a new fish function in `config/fish/functions/`:
+
+## 1. Create the function file
+
+Create `config/fish/functions/<name>.fish`:
+
+```fish
+function <name> --description '<one-line description>'
+  # Function logic here
+end
+```
+
+- One function per file, filename must match function name
+- Always include `--description`
+- Use `--argument-names` for named parameters
+
+## 2. Conventions
+
+- Do NOT use `_tide_` prefix (reserved for tide prompt plugin)
+- Use `--wraps` if the function wraps an existing command
+- For abbreviation-like functions, prefer fish abbreviations
+  in `config/fish/alias.fish` instead
+
+## 3. Validate
+
+Run the fish-validate skill checks:
+
+```bash
+fish --no-execute config/fish/functions/<name>.fish
+fish_indent --check config/fish/functions/<name>.fish
+```

.claude/skills/new-script/SKILL.md

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+---
+name: new-script
+description: >-
+  Scaffold a new helper script in local/bin/ with proper
+  boilerplate, msgr sourcing, and documentation tag.
+user-invocable: true
+allowed-tools: Bash, Read, Write, Edit
+---
+
+When creating a new script in `local/bin/`, follow this template:
+
+## 1. Script file
+
+Create `local/bin/<name>` with:
+
+```bash
+#!/usr/bin/env bash
+# @description <one-line description>
+
+set -euo pipefail
+
+# shellcheck source=msgr
+. "$(dirname "$0")/msgr"
+
+# Script logic here
+```
+
+- Use `msgr` functions for output: `msgr msg`, `msgr run`,
+  `msgr yay`, `msgr err`, `msgr warn`
+- The `@description` tag is required — `dfm scripts` discovers
+  scripts by it
+- POSIX scripts (`/bin/sh`) should NOT source msgr
+
+## 2. Make executable
+
+```bash
+chmod +x local/bin/<name>
+```
+
+## 3. Generate docs
+
+Run `dfm docs script <name>` or manually create `local/bin/<name>.md`
+with a usage summary.
+
+## 4. Validate
+
+Run the shell-validate skill checks (syntax + shellcheck).
+
+## Naming conventions
+
+- `x-` prefix for standalone utilities (e.g., `x-ssl-expiry-date`)
+- Short names for frequently used commands (e.g., `a`, `ad`, `ae`)
+- `git-` prefix for git subcommands (e.g., `git-dirty`)