[Cloudflare] OAuth + API Worker deployment PoC (#76)

[Regstar2]

Scope

Implements the Android PoC from #76 without replacing the existing Wrangler/manual flow.

• Authorization Code + PKCE (S256), no client secret in APK
• configurable Cloudflare OAuth client ID/scopes
• multiple independent OAuth logins and multiple accounts per login
• access tokens encrypted with Android Keystore; no refresh-token persistence
• deploy/redeploy/delete the current chunk-relay Worker via Cloudflare multipart API
• declarative SQLite Durable Object export and CHUNK_RELAY binding
• workers.dev enablement + smoke check
• successful endpoint is added to Worker Pool without duplicates
• current Worker sources are copied into generated Android assets at build time
• RU/EN PoC UI and implementation notes

Verification

• Added RFC 7636 PKCE test and Worker-name normalization test.
• CI still needs to run on this PR.
• Real OAuth consent/deployment requires a registered Cloudflare OAuth client and Android device; keep [Cloudflare] PoC: deploy Workers from Android via Cloudflare OAuth + API #76 open until that manual gate passes.

Refs #76

[Regstar2]

Закрываю без merge вместе с #76. Cloudflare public OAuth требует верифицированный собственный домен для Client URL; без этой инфраструктурной зависимости фича не подходит для текущего проекта. Ветка/PoC остаются в истории при необходимости вернуться к эксперименту позже.