M0: C11 PocketBox foundation for WR703N and Mango

[pgousdal]

M0 scope

• C11/POSIX host prototype with local HTTP homepage and safe single-file download path
• ASCII-over-TCP terminal menu (full Telnet negotiation planned for M3)
• Smoke tests and GitHub Actions host CI
• Hardware qualification, architecture, roadmap, security guidance, MIT license

Boundaries

No ARM support, no device-qualified OpenWrt binaries, no flashing, no public network binding or uploads at M0. Hardware acceptance remains pending.

Verification

CI is configured; tests must be checked after workflow execution. Please review before merging.