Add Groq platform (provider 4)

The 7th registry row and the first pure-pattern cycle: id "groq",
GROQ_API_KEY > auth.json "groq" scope, https://api.groq.com/openai/v1
with KIGI_GROQ_BASE_URL override, OpenAI listing + ChatCompletions +
Passthrough dialect (Groq accepts the OpenAI-style reasoning_effort
scalar verbatim), enrichment-backed metadata with the tool-calling
restriction (the listing carries whisper/tts/guard noise — 8 of 15
enrichment entries are non-chat).

Review verdict: faithful pattern repeat, zero blocking findings — row
facts verified against live Groq docs, registry integrity at 7, e2e
proven strong on both axes (restriction + dialect mapping). Added the
recommended pin: managed keys split on the FIRST slash, so Groq's
provider-native slashed ids (openai/gpt-oss-120b and 10 more) round-trip
as groq/openai/gpt-oss-120b → (Groq, openai/gpt-oss-120b).

Also fixes a pre-existing test race this cycle surfaced: the enterprise-
endpoints test asserted moonshot's fixed base while non-serial, racing
serial tests that legitimately point KIGI_MOONSHOT_CN_BASE_URL at
wiremock; now serial + env-unset like its documented siblings. Two
display-only advisories logged as tracked debt (Groq's delta.reasoning
field invisible in the TUI; platform-generic rate-limit copy).

crates/codegen/kigi-shell/src/agent/auth_method.rs

@@ -594,7 +594,8 @@ mod tests {
                 MOONSHOT_AI_METHOD_ID,
                 "openai",
                 "anthropic",
-                "deepseek"
+                "deepseek",
+                "groq"
             ]
         );
         assert_eq!(default_id(&built), Some(XAI_API_KEY_METHOD_ID));
@@ -623,7 +624,8 @@ mod tests {
                 MOONSHOT_AI_METHOD_ID,
                 "openai",
                 "anthropic",
-                "deepseek"
+                "deepseek",
+                "groq"
             ]
         );
         assert_eq!(default_id(&built), Some(CACHED_TOKEN_AUTH_METHOD_ID));
@@ -645,7 +647,8 @@ mod tests {
                 MOONSHOT_AI_METHOD_ID,
                 "openai",
                 "anthropic",
-                "deepseek"
+                "deepseek",
+                "groq"
             ]
         );
         assert_eq!(default_id(&built), Some(CACHED_TOKEN_AUTH_METHOD_ID));
@@ -670,7 +673,8 @@ mod tests {
                 MOONSHOT_AI_METHOD_ID,
                 "openai",
                 "anthropic",
-                "deepseek"
+                "deepseek",
+                "groq"
             ]
         );
         assert_eq!(default_id(&built), None);