feat: add is_subagent flag to agents, fix all lint/type/test issues

- Add is_subagent checkbox to agent editor; subagents are hidden from Chat Settings
- Add is_subagent field to AgentDefinition type, TOML serialization, and API route
- Filter subagents from ModelSelector agent list
- Fix all biome lint/format errors across codebase (useLiteralKeys, noNonNullAssertion, noExplicitAny, formatting, import sorting)
- Fix svelte-check errors (type narrowing in SkillsBrowser, ToolPermissions, SidebarPanel)
- Fix a11y warnings in App.svelte (label-control associations)
- Fix test mocks missing BackgroundShellStore, BackgroundTranscriptStore, createWebSearchTool, createYoutubeTranscribeTool
- Update stale 409 test to match current message-queuing behavior
- Exclude packaging/ and release/ dirs from biome to avoid linting stale build artifacts

2 files changed, 12 insertions, 4 deletions

diff --git a/bin/import-credentials.ts b/bin/import-credentials.ts
index f99f20a..a4ea499 100755
--- a/bin/import-credentials.ts
+++ b/bin/import-credentials.ts
@@ -4,11 +4,19 @@
  * Reads from ~/.claude/.credentials-{1,2}.json and stores them
  * for the configured keys (claude-pro, claude-max).
  */
-import { importCredentialsFromFile, getDatabasePath } from "../packages/core/src/index.js";
+import { getDatabasePath, importCredentialsFromFile } from "../packages/core/src/index.js";
 
 const imports = [
-	{ keyId: "claude-pro", provider: "anthropic", file: `${process.env.HOME}/.claude/.credentials-1.json` },
-	{ keyId: "claude-max", provider: "anthropic", file: `${process.env.HOME}/.claude/.credentials-2.json` },
+	{
+		keyId: "claude-pro",
+		provider: "anthropic",
+		file: `${process.env.HOME}/.claude/.credentials-1.json`,
+	},
+	{
+		keyId: "claude-max",
+		provider: "anthropic",
+		file: `${process.env.HOME}/.claude/.credentials-2.json`,
+	},
 ];
 
 console.log(`Database: ${getDatabasePath()}\n`);
diff --git a/bin/seed-opencode-keys.ts b/bin/seed-opencode-keys.ts
index c461592..c481b8d 100644
--- a/bin/seed-opencode-keys.ts
+++ b/bin/seed-opencode-keys.ts
@@ -2,7 +2,7 @@
 /**
  * Seed API keys from environment variables into the SQLite database.
  */
-import { setApiKey, getDatabasePath } from "../packages/core/src/index.js";
+import { getDatabasePath, setApiKey } from "../packages/core/src/index.js";
 
 console.log(`Database: ${getDatabasePath()}\n`);