feat: switch local to prebuilt update flow and set default Anthropic model to Claude Haiku 4.5

[DJJones66]

Summary

This PR updates runtime mode behavior and default model configuration:

1. Aligns local with prebuilt-image lifecycle behavior (while keeping dev as source-build/hot-reload).
2. Enables startup update checks for local (with dev still excluded).
3. Switches default Anthropic model references from Claude Sonnet 4.6 to Claude Haiku 4.5 across adapter, starter-pack defaults, and UI text.

Changes

Installer / Runtime behavior

• compose.local.yml now uses prebuilt image refs (no source build: blocks).
• install flow:
  • dev builds from source.
  • quickstart, prod, and local pull/use prebuilt images.
• start flow:
  • quickstart, prod, and local run startup update checks.
  • dev continues to skip startup update checks.
• check-update no longer short-circuits in local mode.
• upgrade flow for local now follows image-based pull/restart behavior (same class as quickstart/prod).
• Unified startup URL + browser-open behavior via shared helpers (bash + PowerShell).

Model default updates (Sonnet 4.6 -> Haiku 4.5)

Updated model identifiers and associated UI copy in:

• builds/typescript/adapters/openai-compatible.json
• builds/typescript/memory/init.ts
• builds/typescript/memory/starter-pack/base/AGENT.md
• builds/typescript/memory/starter-pack/base/preferences/default.openrouter-secret-ref.json
• builds/typescript/memory/starter-pack/base/preferences/default.braindrive-managed-secret-ref.json
• builds/typescript/client_web/src/components/settings/SettingsModal.tsx

Documentation updates

• Updated installer docs to reflect:
  • local as prebuilt-image mode.
  • startup update checks for quickstart|prod|local.
  • dev as developer/source-build mode with no startup update checks.

Validation

• Shell syntax checks passed (bash -n) for touched shell scripts.
• docker compose -f installer/docker/compose.local.yml config passed.
• Branch merged with latest origin/main (no conflicts).