feat: initial model catalog with 196 models across 39 providers

Community-maintained TOML catalog for LibreFang. New models can be added
via PR without requiring a LibreFang binary release.

Includes validation script, bilingual docs, and GitHub templates.

providers/lemonade.toml

@@ -0,0 +1,9 @@
+# Lemonade — local NPU accelerated inference
+# Models: 0 (all models discovered dynamically at runtime)
+
+[provider]
+id = "lemonade"
+display_name = "Lemonade"
+api_key_env = "LEMONADE_API_KEY"
+base_url = "http://localhost:8888/api/v1"
+key_required = false