chore: scaffold Kolmekivi from nih-plug-template

A stereo delay/echo plugin. Scaffolded rather than forked: the template
and the plugins built from it diverge on branding immediately, so they
share code by file copy — as codename-206 does — not by merge base. This
repo starts its own history.

Branded with tools/brand-plugin.sh. Everything derives from PLUGIN_NAME
("Kolmekivi" -> kolmekivi / Kolmekivi / KolmekiviParams), so no override
is pinned. CODENAME is set to the repo name and, by convention, stays
there even if the plugin is later renamed.

Two identity constants are now frozen and must never move, because hosts
key saved projects and presets off them:

    CLAP_ID        org.novoyuuparosk.kolmekivi
    VST3_CLASS_ID  KolmekiviDelay!!            (exactly 16 bytes)

Host categorisation is set for a delay rather than left at the template's
generic placeholders — ClapFeature::{AudioEffect,Delay,Stereo} and
Vst3SubCategory::{Fx,Delay}. These decide where the plugin appears in a
host's browser and are not covered by the branding checker, which knows
about names rather than categories.

The DSP is not written. src/lib.rs still carries the template's example
gain parameter, so the plugin builds, bundles and loads while the delay is
implemented.

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

.gitattributes

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+# Shell scripts must keep LF endings. core.autocrlf=true on Windows would
+# otherwise check them out CRLF, which a strict POSIX sh (dash, CI containers)
+# rejects at the shebang.
+*.sh text eol=lf