chore: linting updates

packages/cli/biome.json

···
 	"linter": {
 		"enabled": true,
 		"rules": {
-			"recommended": true
+			"recommended": true,
+			"style": {
+				"noNonNullAssertion": "off"
+			}
 		}
 	},
 	"javascript": {

packages/cli/src/commands/init.ts

···
 
 			const s = spinner();
 			s.start("Connecting to ATProto...");
-			let agent;
+			let agent: Awaited<ReturnType<typeof createAgent>> | undefined;
 			try {
 				agent = await createAgent(credentials);
 				s.stop("Connected!");
-			} catch (error) {
+			} catch (_error) {
 				s.stop("Failed to connect");
 				log.error(
 					"Failed to connect. Check your credentials with 'sequoia auth'.",
···
 				placeholder: "7",
 				validate: (value) => {
 					const num = parseInt(value, 10);
-					if (isNaN(num) || num < 1) {
+					if (Number.isNaN(num) || num < 1) {
 						return "Please enter a positive number";
 					}
 				},
···
 			if (!gitignoreContent.includes(stateFilename)) {
 				await fs.writeFile(
 					gitignorePath,
-					gitignoreContent + `\n${stateFilename}\n`,
+					`${gitignoreContent}\n${stateFilename}\n`,
 				);
 				log.info(`Added ${stateFilename} to .gitignore`);
 			}

packages/cli/src/commands/publish.ts

···
 
 		// Create agent
 		s.start(`Connecting to ${credentials.pdsUrl}...`);
-		let agent;
+		let agent: Awaited<ReturnType<typeof createAgent>> | undefined;
 		try {
 			agent = await createAgent(credentials);
 			s.stop(`Logged in as ${agent.session?.handle}`);

packages/cli/src/commands/sync.ts

···
 		// Create agent
 		const s = spinner();
 		s.start(`Connecting to ${credentials.pdsUrl}...`);
-		let agent;
+		let agent: Awaited<ReturnType<typeof createAgent>> | undefined;
 		try {
 			agent = await createAgent(credentials);
 			s.stop(`Logged in as ${agent.session?.handle}`);

packages/cli/src/lib/atproto.ts

···
 		const segmenter = new Intl.Segmenter("en", { granularity: "grapheme" });
 		const segments = [...segmenter.segment(str)];
 		if (segments.length <= maxGraphemes) return str;
-		return (
-			segments
-				.slice(0, maxGraphemes - 3)
-				.map((s) => s.segment)
-				.join("") + "..."
-		);
+		return `${segments
+			.slice(0, maxGraphemes - 3)
+			.map((s) => s.segment)
+			.join("")}...`;
 	}
 	// Fallback
 	const chars = [...str];
 	if (chars.length <= maxGraphemes) return str;
-	return chars.slice(0, maxGraphemes - 3).join("") + "...";
+	return `${chars.slice(0, maxGraphemes - 3).join("")}...`;
 }
 
 /**

packages/cli/src/lib/markdown.ts

···
 			break;
 		}
 
-		case "filename":
 		default:
 			slug = getSlugFromFilename(path.basename(relativePath));
 			break;