refactor: rename Ai* database identifiers to AI* (AIGOV-369) (#26327)

Adds `ai` to sqlc's `gen.go.initialisms` in `coderd/database/sqlc.yaml`
so the generated DB code follows Go's initialism convention. Adds the
matching `ai` -> `AI` case to the dbgen PascalCase helper
(`scripts/dbgen/main.go`) so the corresponding `dbmem` / mock
identifiers stay in sync. `make gen` regenerates the rest; hand-written
call sites that consume DB-generated identifiers
(`enterprise/audit/table.go`, `coderd/database/modelmethods.go`,
`enterprise/coderd/aigatewaykeys.go`, `coderd/database/dbauthz/*`, etc.)
are updated to match.

Scope is deliberately limited to the database layer:

- `coderd/rbac/*` (resource and scope generators) is untouched —
`ResourceAi*` / `ScopeAi*` constants stay on main's casing.
- `codersdk/*` (Go SDK) is untouched — `codersdk.ResourceAi*` /
`codersdk.APIKeyScopeAi*` constants stay on main's casing, so external
Go SDK consumers see no source-level break.
- `Aibridge*` identifiers (one SQL token `aibridge`, not `ai_bridge`)
are out of scope.

On-the-wire values are unchanged: enum strings, RBAC resource type
strings, API key scope strings, and JSON tags all stay the same. The
HTTP/JSON surface is unaffected.

Refs:
[AIGOV-369](https://linear.app/codercom/issue/AIGOV-369/change-ai-references-in-coderddatabasemodelsgo-to-ai)

🤖 Generated with [Coder Agents](https://coder.com)

coderd/exp_chats_test.go

@@ -1749,7 +1749,7 @@ func TestListChatModels(t *testing.T) {
 		client := newChatClient(t)
 		_ = coderdtest.CreateFirstUser(t, client.Client)
 
-		providerType := database.AiProviderTypeAnthropic
+		providerType := database.AIProviderTypeAnthropic
 		provider := createAIProviderForTest(t, client, string(providerType), "")
 
 		contextLimit := int64(4096)
@@ -3997,7 +3997,7 @@ func TestUpdateChatModelConfig(t *testing.T) {
 		require.NoError(t, err)
 
 		modelConfig := dbgen.ChatModelConfig(t, db, database.ChatModelConfig{
-			Provider:     string(database.AiProviderTypeOpenai),
+			Provider:     string(database.AIProviderTypeOpenai),
 			Model:        "anthropic/claude-opus-4.6",
 			AIProviderID: uuid.NullUUID{UUID: aiProvider.ID, Valid: true},
 		})