feat(aiproxy): add authenticated proxy for OpenAI-compatible APIs and MCP servers

Hides upstream URLs and keys behind the security layer. Per-upstream roles,
model/tool allowlists, per-user rate limits, Before/AfterProxy hooks, audit
sink, Prometheus metrics (metrics.AIProxyRecorder) and upstreams loaded from
the resolvespec_ai_proxies stored procedure.

pkg/aiproxy/resolvespec_ai_proxies.sql

@@ -0,0 +1,42 @@
+-- aiproxy upstream definitions (PostgreSQL), same contract as the resolvespec security procedures.
+-- ProcStore calls: SELECT p_success, p_error, p_data FROM resolvespec_ai_proxies()
+-- Replace the function body to source the definitions from anywhere; keep the signature.
+--
+-- p_data: JSON array, one object per upstream
+--   name, kind ('openai'|'mcp'), base_url                              required
+--   api_key, auth_header, auth_format, headers (object)                optional
+--   allowed_roles (array), allowed (array: models for openai, tools for mcp)
+--   rate_per_second, rate_burst, timeout_seconds, enabled (default true)
+
+CREATE TABLE IF NOT EXISTS ai_proxies (
+    name            text PRIMARY KEY,
+    kind            text NOT NULL CHECK (kind IN ('openai', 'mcp')),
+    base_url        text NOT NULL,
+    api_key         text,
+    auth_header     text,
+    auth_format     text,
+    headers         jsonb,
+    allowed_roles   jsonb,
+    allowed         jsonb,
+    rate_per_second double precision,
+    rate_burst      integer,
+    timeout_seconds integer,
+    enabled         boolean NOT NULL DEFAULT true
+);
+
+CREATE OR REPLACE FUNCTION resolvespec_ai_proxies()
+RETURNS TABLE(p_success boolean, p_error text, p_data jsonb) AS $$
+DECLARE
+    v_data jsonb;
+BEGIN
+    SELECT COALESCE(jsonb_agg(to_jsonb(p) - 'enabled' ORDER BY p.name), '[]'::jsonb)
+    INTO v_data
+    FROM ai_proxies p
+    WHERE p.enabled = true;
+
+    RETURN QUERY SELECT true, NULL::text, v_data;
+EXCEPTION
+    WHEN OTHERS THEN
+        RETURN QUERY SELECT false, SQLERRM::text, '[]'::jsonb;
+END;
+$$ LANGUAGE plpgsql;