feat: record model thoughts (#22676)

Depends on https://github.com/coder/aibridge/pull/203
Closes https://github.com/coder/internal/issues/1337

---------

Signed-off-by: Danny Kopping <danny@coder.com>

coderd/database/migrations/000442_aibridge_model_thoughts.down.sql

@@ -0,0 +1,3 @@
+DROP INDEX idx_aibridge_model_thoughts_interception_id;
+
+DROP TABLE aibridge_model_thoughts;

coderd/database/migrations/000442_aibridge_model_thoughts.up.sql

@@ -0,0 +1,10 @@
+CREATE TABLE aibridge_model_thoughts (
+    interception_id UUID NOT NULL,
+    content TEXT NOT NULL,
+    metadata jsonb,
+    created_at TIMESTAMPTZ NOT NULL
+);
+
+COMMENT ON TABLE aibridge_model_thoughts IS 'Audit log of model thinking in intercepted requests in AI Bridge';
+
+CREATE INDEX idx_aibridge_model_thoughts_interception_id ON aibridge_model_thoughts(interception_id);

coderd/database/migrations/testdata/fixtures/000442_aibridge_model_thoughts.up.sql

@@ -0,0 +1,13 @@
+INSERT INTO
+    aibridge_model_thoughts (
+        interception_id,
+        content,
+        metadata,
+        created_at
+    )
+VALUES (
+    'be003e1e-b38f-43bf-847d-928074dd0aa8', -- from 000370_aibridge.up.sql
+    'The user is asking about their workspaces. I should use the coder_list_workspaces tool to retrieve this information.',
+    '{"source": "commentary"}',
+    '2025-09-15 12:45:19.123456+00'
+);