chore: bootstrap hermes-ui skeleton from 0.6.29 snapshot

Import the client, server, skills, tests, and build scripts as the starting
point for the rebuild, then trim the surfaces this project does not ship:
Electron desktop packaging, the marketing website, and the ESP32 firmware
tree. CI keeps the web build, e2e, lockfile, release, and Docker workflows.

Rename the package and CLI entry points to hermes-ui, drop the prepare hook so
npm ci no longer triggers a build, and drop the removed tsconfig and nodemon
references. Rewrite AGENTS.md, ARCHITECTURE.md, DEVELOPMENT.md, and the READMEs
so the documented package map and hard rules match this repository.

reference_code/ is ignored: it is a read-only snapshot, not an input to the build.

tests/server/safe-file-store-backup-fallback.test.ts

@@ -0,0 +1,65 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+const {
+  mockCopyFile,
+  mockMkdir,
+  mockReadFile,
+  mockRename,
+  mockRm,
+  mockWriteFile,
+} = vi.hoisted(() => ({
+  mockCopyFile: vi.fn(),
+  mockMkdir: vi.fn(),
+  mockReadFile: vi.fn(),
+  mockRename: vi.fn(),
+  mockRm: vi.fn(),
+  mockWriteFile: vi.fn(),
+}))
+
+vi.mock('fs/promises', () => ({
+  copyFile: mockCopyFile,
+  mkdir: mockMkdir,
+  readFile: mockReadFile,
+  rename: mockRename,
+  rm: mockRm,
+  writeFile: mockWriteFile,
+}))
+
+afterEach(() => {
+  vi.clearAllMocks()
+})
+
+describe('SafeFileStore backup fallback', () => {
+  it('uses a timestamped backup when the default backup cannot be overwritten', async () => {
+    mockCopyFile
+      .mockRejectedValueOnce(Object.assign(new Error('permission denied'), { code: 'EACCES' }))
+      .mockResolvedValueOnce(undefined)
+    mockMkdir.mockResolvedValue(undefined)
+    mockWriteFile.mockResolvedValue(undefined)
+    mockRename.mockResolvedValue(undefined)
+
+    const { SafeFileStore } = await import('../../packages/server/src/services/safe-file-store')
+    const store = new SafeFileStore()
+
+    await store.writeText('/tmp/config.yaml', 'model:\n  default: new\n', { backup: true })
+
+    expect(mockCopyFile).toHaveBeenCalledTimes(2)
+    expect(mockCopyFile).toHaveBeenNthCalledWith(1, '/tmp/config.yaml', '/tmp/config.yaml.bak')
+    expect(mockCopyFile.mock.calls[1][0]).toBe('/tmp/config.yaml')
+    expect(mockCopyFile.mock.calls[1][1]).toMatch(/^\/tmp\/config\.yaml\.bak\.\d+\./)
+    expect(mockWriteFile).toHaveBeenCalledWith(expect.stringContaining('/tmp/config.yaml.tmp.'), 'model:\n  default: new\n', 'utf-8')
+    expect(mockRename).toHaveBeenCalledWith(expect.stringContaining('/tmp/config.yaml.tmp.'), '/tmp/config.yaml')
+  })
+
+  it('preserves explicit backup path failures', async () => {
+    mockCopyFile.mockRejectedValueOnce(Object.assign(new Error('permission denied'), { code: 'EACCES' }))
+    mockMkdir.mockResolvedValue(undefined)
+
+    const { SafeFileStore } = await import('../../packages/server/src/services/safe-file-store')
+    const store = new SafeFileStore()
+
+    await expect(store.writeText('/tmp/config.yaml', 'new', { backup: true, backupPath: '/tmp/custom.bak' })).rejects.toThrow('permission denied')
+    expect(mockCopyFile).toHaveBeenCalledTimes(1)
+    expect(mockWriteFile).not.toHaveBeenCalled()
+  })
+})