Add OIDC sign-in, group-derived roles and declarative instance configuration

Workspaces, group mappings and sign-in methods now come from a configuration
file synchronized at startup; workspaces dropped from it are disabled, never
deleted. Instance administrators (a new role) see and help every workspace and
may delete disabled ones; workspace administrators and employees are derived
from the user's groups at every SSO sign-in or administrator edit, and the
employee permission set belongs to the workspace. Self-registration is gone:
users come from SSO (only when their groups map) or from the administrator.
Break-glass bootstrap accounts get an HMAC-derived hourly password that all
replicas agree on. First SSO sign-in links a matching email contact to the
user. The demo runs on the same model with a generated per-start password.

Co-Authored-By: Claude <noreply@anthropic.com>

tests/browser-advanced-demos.cjs

@@ -1,7 +1,7 @@
 const assert=require('node:assert/strict');
 (async()=>{const browser=await require('./support/browser.cjs').launchBrowser();try{
  for(const [user,names] of [['alice',['Acme Engineering','Customer Support','Regional Platform','Commerce Operations']],['bob',['Acme Engineering','Regional Platform']],['carol',['Acme Engineering','Customer Support','Commerce Operations']],['dave',['Acme Engineering']],['erin',['Acme Engineering']]]){
- const page=await browser.newPage();const errors=[];page.on('pageerror',e=>errors.push(e.message));await page.goto('http://127.0.0.1:3000/');await page.getByLabel('Username',{exact:true}).fill(user);await page.getByLabel('Password',{exact:true}).fill('meguri-demo-only');await page.getByRole('button',{name:'Sign in',exact:true}).click();await page.waitForFunction(()=>window.Alpine&&Alpine.$data(document.body).workspace);
+ const page=await browser.newPage();const errors=[];page.on('pageerror',e=>errors.push(e.message));await page.goto('http://127.0.0.1:3000/');await page.getByLabel('Username',{exact:true}).fill(user);await page.getByLabel('Password',{exact:true}).fill(await require('./support/browser.cjs').demoPassword());await page.getByRole('button',{name:'Sign in',exact:true}).click();await page.waitForFunction(()=>window.Alpine&&Alpine.$data(document.body).workspace);
  const teams=await page.evaluate(()=>Alpine.$data(document.body).directoryState.workspaces);assert.deepEqual(teams.map(t=>t.name).filter(n=>['Acme Engineering','Customer Support','Regional Platform','Commerce Operations'].includes(n)).sort(),names.sort());
  if(user==='alice'){const schedules=await page.evaluate(()=>Alpine.$data(document.body).doc.schedules);assert.equal(schedules.filter(s=>s.type==='priority').length,6);assert(schedules.filter(s=>s.type==='priority').every(s=>s.participants.length>=2&&s.participants.length<=3));assert.equal(schedules.find(s=>s.type==='rotation').participants.length,5);}
  if(user==='alice')for(const name of ['Regional Platform','Commerce Operations']){