feat: add a branding consistency checker

Adapted from musiikki/codename-206, where the same script guards a single
plugin. It matters more here: renaming is the first thing anyone does with
a template, and identity is duplicated across Cargo.toml, bundler.toml,
src/lib.rs and the docs with nothing keeping them in agreement. A
half-finished rename builds a bundle under one name while the docs and
deploy script look for another.

Changes from the codename-206 original:

- Checks for files this repo does not ship (deploy.ps1) report as `skip`
  rather than FAIL, and start enforcing once the file appears.
- STALE ships pre-seeded with this template's own placeholders, and each
  entry is skipped while it is still part of a canonical value. That makes
  renaming self-checking: entries arm themselves as you change the value
  they belong to, with no bookkeeping. Substring rather than equality,
  because placeholders nest — "your-domain" lives inside the canonical
  CLAP_ID.
- Covers identity this template carries that codename-206's did not:
  VENDOR, EMAIL, the Cargo homepage feeding Plugin::URL, that the `env!`
  indirection is still in place, and the README's bundle command.
- Asserts CLAP_ID is reverse-DNS safe. A stray capital or space there is
  not a compile error, it is a silent identity change between machines.

Two placeholder spellings had to move to avoid false positives, since a
checker that cries wolf trains you to ignore it: bundler.toml's comment
contained the literal "Plugin Name", and the CLAP_ID TODO spelled the
placeholder a third way that matched neither the constant nor the STALE
list. The TODO now illustrates the form instead of repeating a placeholder.

.gitattributes pins *.sh to LF so core.autocrlf=true on Windows cannot
check the script out with a CRLF shebang that dash rejects.

Verified three ways: clean template passes, a partial rename names every
drifted file, and a complete rename passes and still compiles.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WHt4DykxXaQnyaJfyS8KCn

bundler.toml

@@ -1,7 +1,7 @@
 # Metadata for NIH-plug's `cargo xtask bundle <package>` bundler.
 #
 # [package_name]
-# name = "Human Readable Plugin Name"  # defaults to <package_name>
+# name = "Human Readable Bundle Name"  # defaults to <package_name>
 
 [nih_plug_template]
 name = "Plugin Name"