Improve operational UX, recovery flows, and action safety

Implement the approved UX review across Fleet, Betas, Library, deployments, and Settings. Add reviewed promotion and reconciliation plans, atomic queued-removal cancellation, recoverable beta drafts and launch inputs, accessible controls, and mobile improvements.

Validated with 473 tests, a clean typecheck, production build, and isolated desktop/mobile browser walkthroughs. Include the review and implementation coverage notes.

tests/unit/config-inspect.test.ts

@@ -1,7 +1,7 @@
 import { describe, expect, it } from 'vitest';
 import { inspectConfig, type ConfigLayer } from '../../src/lib/server/fleet/config-inspect.js';
 import { composeServerCfg } from '../../src/lib/server/fleet/config-compose.js';
-import { changeConfigValue, configWarnings } from '../../src/lib/config-workbench.js';
+import { addConfigSetting, changeConfigValue, configWarnings } from '../../src/lib/config-workbench.js';
 
 const base = (text: string): ConfigLayer => ({ text, source: { id: 1, name: 'Base', version: 2, kind: 'baseline' } });
 const overlay = (id: number, text: string): ConfigLayer => ({ text, source: { id, name: `Overlay ${id}`, version: 3, kind: 'config' } });
@@ -63,6 +63,17 @@ describe('config source inspection', () => {
 });
 
 describe('config settings editor', () => {
+    it('adds a structured value without altering existing content or line endings', () => {
+        expect(addConfigSetting('// comment\r\nset x 1', 'sv_hostname', 'Cherry lobby')).toBe('// comment\r\nset x 1\r\nset sv_hostname "Cherry lobby"\r\n');
+        expect(addConfigSetting('', 'g_inactivity', '0')).toBe('set g_inactivity 0\n');
+    });
+
+    it('rejects duplicate keys, missing values, and multiline assignments', () => {
+        expect(() => addConfigSetting('set FOO 1', 'foo', '2')).toThrow('already exists');
+        expect(() => addConfigSetting('', 'bad key', '1')).toThrow('setting name');
+        expect(() => addConfigSetting('', 'key', '// no value')).toThrow('value');
+        expect(() => addConfigSetting('', 'key', '1\nset other 2')).toThrow('one line');
+    });
     it('changes only the selected assignment, preserving CRLF, spacing and raw commands', () => {
         const text = '// note\r\n  set  a   "1" // original\r\nexec other.cfg\r\nset a 5\n';
         expect(changeConfigValue(text, 1, '"2" // changed')).toBe('// note\r\n  set  a   "2" // changed\r\nexec other.cfg\r\nset a 5\n');