Give the project an About page, and fold Our Team and Green Life into it

[openipc-ai]

Part of #206 (Phase 1). Depends on nothing. Blocks #217.

Why

June planned a dedicated About page and, until it existed, sent /about to /community with a 302 so the redirect would not be cached forever (config/routes.rb:61-65). Three weeks on, the 302 is still there. Meanwhile two legacy pages carry the material an About page is made of: /our-team (494 lines, 36 hardcoded member cards with GitHub avatars, in two sections "IPC Core" and "URLLC and FPV") and /green_life (four translated paragraphs on why open firmware extends a camera's life). Both render in the old container, both sit in the Community dropdown, neither is linked from the seven new pages. #116 asks the site to say that OpenIPC is an umbrella for several activities; that sentence belongs on the About page.

What to change

• pages#about, /about in the localised scope, app/views/pages/about.html.erb full-bleed, three locales in config/locales/pages.{en,ru,zh}.yml. Sections: what OpenIPC is (the umbrella: firmware, Majestic, the WebUI, the tooling, the labs), who makes it (the team), and why it matters (the longevity and e-waste argument from Green Life).
• The team moves out of markup into PagesHelper data, the way PARTNER_GROUPS and RU_INTEGRATORS already are, so adding a person is one line. Avatars keep coming from avatars.githubusercontent.com; members commented out in the old template are carried across as commented-out entries with their handles, not silently dropped.
• The 302 goes. /our-team and /green_life become 301s to /about (keeping the query string, like the existing keep_query redirects), with a test each in test/controllers/redirects_test.rb.
• The Community dropdown (app/views/layouts/_navbar.html.erb) and the Project column of the footer link /about; the Our Team and Green Life entries go.
• test/controllers/relaunch_pages_test.rb:80 and test/controllers/page_metadata_test.rb:88 use /our-team as the non-fullwidth control. They pick another legacy page (/stages-of-firmware-development until Bring the development-stages glossary into the new design #213 lands).
• The Chinese copy goes through the reviewer from Have the Chinese copy of the seven relaunch pages read by a native speaker #207 before the page is linked.

Done means

• /about, /ru/about, /zh/about render with no missing translation; the page is in relaunch_pages_test.rb's list.
• /our-team and /green_life answer 301 to /about in the redirect test.
• Screenshots of the page in three locales at 2x are attached here before any PR is opened.