chore: rename project from gosearch to kafka

A search engine named after a man who proved answers don't exist.

Renamed everywhere user-facing:
- Brand name, UI titles, OpenSearch description, CSS filename
- Docker service name, NixOS module (services.kafka)
- Cache key prefix (kafka:), User-Agent strings (kafka/0.1)
- README, config.example.toml, flake.nix descriptions

Kept unchanged (internal):
- Go module path: github.com/ashie/gosearch
- Git repository URL: git.ashisgreat.xyz/penal-colony/gosearch
- Binary entrypoint: cmd/searxng-go

README.md

@@ -1,4 +1,4 @@
-# gosearch
+# kafka
 
 A privacy-respecting, open metasearch engine written in Go. SearXNG-compatible API with an HTML frontend, designed to be fast, lightweight, and deployable anywhere.
 
@@ -12,7 +12,7 @@ A privacy-respecting, open metasearch engine written in Go. SearXNG-compatible A
 - **Valkey cache** — optional Redis-compatible caching with configurable TTL
 - **Rate limiting** — three layers: per-IP, burst, and global (all disabled by default)
 - **CORS** — configurable origins for browser-based clients
-- **OpenSearch** — browsers can add gosearch as a search engine from the address bar
+- **OpenSearch** — browsers can add kafka as a search engine from the address bar
 - **Graceful degradation** — individual engine failures don't kill the whole search
 - **Docker** — multi-stage build, ~20MB runtime image
 - **NixOS** — native NixOS module with systemd service
@@ -23,7 +23,7 @@ A privacy-respecting, open metasearch engine written in Go. SearXNG-compatible A
 
 ```bash
 git clone https://git.ashisgreat.xyz/penal-colony/gosearch.git
-cd gosearch
+cd kafka
 go build ./cmd/searxng-go
 ./searxng-go -config config.toml
 ```
@@ -41,28 +41,28 @@ docker compose up -d
 Add to your flake inputs:
 
 ```nix
-inputs.gosearch.url = "git+https://git.ashisgreat.xyz/penal-colony/gosearch.git";
+inputs.kafka.url = "git+https://git.ashisgreat.xyz/penal-colony/gosearch.git";
 ```
 
 Enable in your configuration:
 
 ```nix
-imports = [ inputs.gosearch.nixosModules.default ];
+imports = [ inputs.kafka.nixosModules.default ];
 
-services.gosearch = {
+services.kafka = {
   enable = true;
   openFirewall = true;
   baseUrl = "https://search.example.com";
-  # config = "/etc/gosearch/config.toml";  # default
+  # config = "/etc/kafka/config.toml";  # default
 };
 ```
 
 Write your config:
 
 ```bash
-sudo mkdir -p /etc/gosearch
-sudo cp config.example.toml /etc/gosearch/config.toml
-sudo $EDITOR /etc/gosearch/config.toml
+sudo mkdir -p /etc/kafka
+sudo cp config.example.toml /etc/kafka/config.toml
+sudo $EDITOR /etc/kafka/config.toml
 ```
 
 Deploy: