feat(docker): harden session mode + File Viewer button (v1.4.1)

Docker cases: seamless Claude auth (seed ~/.claude.json instead of the
corruption-prone single-file mount), full credential-store isolation for
claude + codex/gemini/gcloud/opencode (share only transcripts/rollouts,
seed the rest), auto-build the base image on first use, C.UTF-8 locale
(fixes box-drawing), collapsed/shortened Create-Case UI + short "(docker)"
case-menu tags, and w<n>-<case> tab naming for docker/remote sessions.
Also: opt-in File Viewer header button; fix a TZ-boundary flaky test.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/schemas.ts

@@ -536,6 +536,9 @@ export const QuickStartSchema = z.object({
     .string()
     .regex(/^[a-zA-Z0-9_-]+$/, 'Invalid case name format. Use only letters, numbers, hyphens, underscores.')
     .optional(),
+  /** Display name for the created session tab (e.g. w1-mycase). Cosmetic; the durable
+   *  mux/container names derive from the session id, not this. Defaults server-side. */
+  sessionName: z.string().max(128).optional(),
   mode: z.enum(['claude', 'shell', 'opencode', 'codex', 'gemini']).optional(),
   openCodeConfig: OpenCodeConfigSchema,
   codexConfig: CodexConfigSchema,