feat: agent builder, CWD support, auto-save, UI polish, unavailable tool handling

- Agent Builder: full CRUD with card grid, drag-and-drop model reorder, edit/delete
- Auto-save on edit with 600ms debounce, AbortController for concurrency, fieldset disabled until name entered
- Agent definitions stored as TOML with cwd field, loaded from global/project dirs
- Working directory: per-tab CWD override in Chat Settings, agent default CWD, auto-create on first message
- CWD validation: check-dir endpoint with ~ expansion, real-time validity indicator
- Subagent CWD validated against parent's effective CWD using path.relative
- Unavailable tool calls: caught gracefully, shown as tool call with error badge, model retries
- UI: tab bar border radius, sidebar border removed, chat input ghost style, scroll-to-bottom rectangle
- Skills dir collapse uses CSS rotation, Model Choice renamed to Chat Settings, System Prompt view removed
- Reusable SkillsBrowser/ToolPermissions with external mode for Agent Builder
- ModelSelector: Agent/Manual toggle, agent list, Agent Settings link
- Page router, skills recursive scanning, bin/up gopass removed, docker volume mounts

3 files changed, 29 insertions, 14 deletions

diff --git a/packages/core/src/config/loader.ts b/packages/core/src/config/loader.ts
index 3b4d733..bccbb8f 100644
--- a/packages/core/src/config/loader.ts
+++ b/packages/core/src/config/loader.ts
@@ -28,7 +28,9 @@ export function loadConfig(dir: string): DispatchConfig {
 			// File doesn't exist — return empty default
 			return DEFAULT_CONFIG;
 		}
-		console.warn(`dispatch: failed to parse dispatch.toml: ${err instanceof Error ? err.message : String(err)}`);
+		console.warn(
+			`dispatch: failed to parse dispatch.toml: ${err instanceof Error ? err.message : String(err)}`,
+		);
 		throw err;
 	}
 
diff --git a/packages/core/src/config/schema.ts b/packages/core/src/config/schema.ts
index 2cd8d55..ef10b65 100644
--- a/packages/core/src/config/schema.ts
+++ b/packages/core/src/config/schema.ts
@@ -1,8 +1,4 @@
-import type {
-	ConfigError,
-	DispatchConfig,
-	KeyDefinition,
-} from "../types/index.js";
+import type { ConfigError, DispatchConfig, KeyDefinition } from "../types/index.js";
 
 function isRecord(value: unknown): value is Record<string, unknown> {
 	return typeof value === "object" && value !== null && !Array.isArray(value);
@@ -33,19 +29,28 @@ function validatePermissions(
 	const result: Record<string, string | Record<string, string>> = {};
 	for (const [key, value] of Object.entries(raw)) {
 		if (!isPermissionsValue(value)) {
-			errors.push({ path: `${path}.${key}`, message: "must be a string or a flat string-keyed object" });
+			errors.push({
+				path: `${path}.${key}`,
+				message: "must be a string or a flat string-keyed object",
+			});
 			continue;
 		}
 		if (typeof value === "string") {
 			if (!isValidAction(value)) {
-				errors.push({ path: `${path}.${key}`, message: `invalid action "${value}"; must be "allow", "deny", or "ask"` });
+				errors.push({
+					path: `${path}.${key}`,
+					message: `invalid action "${value}"; must be "allow", "deny", or "ask"`,
+				});
 				continue;
 			}
 		} else {
 			let hasError = false;
 			for (const [pattern, action] of Object.entries(value)) {
 				if (!isValidAction(action)) {
-					errors.push({ path: `${path}.${key}.${pattern}`, message: `invalid action "${action}"; must be "allow", "deny", or "ask"` });
+					errors.push({
+						path: `${path}.${key}.${pattern}`,
+						message: `invalid action "${action}"; must be "allow", "deny", or "ask"`,
+					});
 					hasError = true;
 				}
 			}
@@ -80,7 +85,9 @@ function validateKey(raw: unknown, path: string, errors: ConfigError[]): KeyDefi
 			id: raw["id"] as string,
 			provider: raw["provider"] as string,
 			base_url: raw["base_url"] as string,
-			...(typeof raw["credentials_file"] === "string" ? { credentials_file: raw["credentials_file"] } as Pick<KeyDefinition, "credentials_file"> : {}),
+			...(typeof raw["credentials_file"] === "string"
+				? ({ credentials_file: raw["credentials_file"] } as Pick<KeyDefinition, "credentials_file">)
+				: {}),
 		};
 	}
 
diff --git a/packages/core/src/config/watcher.ts b/packages/core/src/config/watcher.ts
index 42b2f87..70821ed 100644
--- a/packages/core/src/config/watcher.ts
+++ b/packages/core/src/config/watcher.ts
@@ -1,5 +1,5 @@
-import { watch } from "chokidar";
 import { join } from "node:path";
+import { watch } from "chokidar";
 import type { DispatchConfig } from "../types/index.js";
 import { loadConfig } from "./loader.js";
 
@@ -26,7 +26,9 @@ export function createConfigWatcher(
 				const config = loadConfig(dir);
 				onChange(config);
 			} catch (err) {
-				console.warn(`dispatch: retaining last known config due to parse error: ${err instanceof Error ? err.message : String(err)}`);
+				console.warn(
+					`dispatch: retaining last known config due to parse error: ${err instanceof Error ? err.message : String(err)}`,
+				);
 			}
 		}, 300);
 	};
@@ -36,7 +38,9 @@ export function createConfigWatcher(
 	watcher.on("unlink", handleChange);
 
 	watcher.on("error", (err) => {
-		console.warn(`dispatch: config watcher error: ${err instanceof Error ? err.message : String(err)}`);
+		console.warn(
+			`dispatch: config watcher error: ${err instanceof Error ? err.message : String(err)}`,
+		);
 	});
 
 	return {
@@ -46,7 +50,9 @@ export function createConfigWatcher(
 				debounceTimer = null;
 			}
 			watcher.close().catch((err) => {
-				console.warn(`dispatch: error closing config watcher: ${err instanceof Error ? err.message : String(err)}`);
+				console.warn(
+					`dispatch: error closing config watcher: ${err instanceof Error ? err.message : String(err)}`,
+				);
 			});
 		},
 	};