Docs backfill for social bar v2 (9873eed): schema v6->v8 in TASKS.md/ai.md, social bar architecture section + Simple Icons CC0 notice, README structure rows, HANDOFF rewritten (committed+pushed)

HANDOFF.md

@@ -7,8 +7,10 @@
 
 ## Session state (last updated: 2026-08-12)
 
-- **Branch:** `main` (work UNCOMMITTED — see dirty list). Includes the previous
-  session's socials v2 fixes + this session's fediverse-service-icon work.
+- **Branch:** `main` — the social bar v2 push is **committed + pushed** (`9873eed`,
+  18 files, +1878/−321, 112 tests passing, 0 warnings). Working tree is **dirty
+  with the post-push docs backfill only** (ai.md, README.md, TASKS.md schema
+  section, THIRD-PARTY-NOTICES.txt) — ready to commit when the user says so.
 - **Finished this session (round 3):** user's live-test report said the mastodon
   icon still didn't show for `@gramps@llamachile.tube`. Root cause: the identity
   domain `llamachile.tube` is YunoHost-SSO-gated — `/.well-known/nodeinfo`,
@@ -20,7 +22,7 @@
   identity domain fails, follows the root redirect (`ResolveInstanceHostAsync`,
   reads `resp.RequestMessage.RequestUri.Host`) and re-runs the nodeinfo lookup
   on the resolved host. New test `FediverseHandle_RootRedirectToSubdomain_ResolvesSoftware`.
-  Build: **0 warnings**. Tests: **111 passing**.
+  Build: **0 warnings**. Tests: **112 passing**.
 - **What landed (all rounds this session):**
   1. **Fediverse icon resolution** — `DetectService` maps `@user@domain` to the
      new `SocialService.Fediverse` (was `Link`/chain icon). On validate,
@@ -61,9 +63,9 @@
   - Round-3 redirect fallback fires only when identity-domain nodeinfo fails;
     the root follow happens automatically (HttpClient default auto-redirect),
     and `RequestMessage.RequestUri.Host` is read from the final response.
-- **Next step:** show the user the fixes and let them decide whether to commit.
-  Nothing queued beyond that — do not expand the task queue on your own.
-  (`ytLive.Tests`/`bin` + `/obj` are dirty build artifacts, not hand-authored.)
+- **Next step:** commit + push the docs backfill (ai.md / README.md / TASKS.md
+  schema section / THIRD-PARTY-NOTICES.txt) once the user confirms. Nothing
+  else queued — do not expand the task queue on your own.
 
 - **Secret/DB/port facts live:** OAuth client id/secret in `Helpers/OAuthCredentials.cs`;
   OAuth session token in `Helpers/TokenStore.cs` (DPAPI → `%APPDATA%\ytLlive\ytLlive.auth`);