fix review findings: sync stale v1/removed-event doc references

Codex's re-confirmation pass verified both blocker fixes correct but found
doc/comment drift the fix commit missed:

- session/index.ts + session/README.md: "minimal v1 header" → "minimal header
  (stamped with the current SESSION_FORMAT_VERSION)" — the version is 0, not 1.
- session/index.ts deriveMessages comment listed "usage, and errors" as trace
  data — those standalone events no longer exist; only boundaries + chunks are.
- session-persistence RFC: "no v1 migration" → the pinned-v0 pre-release stance.
- collapse-trace-only RFC format-version note: reframed off the "bump the
  version and reject" wording (which now reads as the OTHER AGENTS.md stance)
  onto the pinned-0 unstable stance the session log actually uses.
- agent-loop/loop.ts finishError JSDoc: "with a logged `error` event" → the
  failure is recorded on turn/end.reason (no standalone error event).
- acp/acp-feature-support.md (two spots): usage is recorded on assistant/message
  now, not as standalone internal usage events.
- Regenerate the cordis catalog (finishError JSDoc line shift).

packages/ui/acp/acp-feature-support.md

@@ -87,7 +87,7 @@ These are capabilities the bridge would *drive* on the editor. The harness runs
 | `available_commands_update` | S | ❌ | ✅ | ✅ | No slash commands advertised. |
 | `current_mode_update` | S | ❌ | ✅ | ✅ | No session modes. |
 | `config_option_update` | S | ❌ | ✅ | ✅ | No config options. |
-| `usage_update` | S | ❌ | ✅ | ✅ | Token/cost reporting not surfaced (the harness HAS usage events internally). |
+| `usage_update` | S | ❌ | ✅ | ✅ | Token/cost reporting not surfaced (the harness records token usage internally on `assistant/message`). |
 | `session_info_update` | S | ❌ | ⚠️ | ⚠️ | Session title/metadata not pushed. |
 
 ## 5. Tool-call rendering
@@ -148,7 +148,7 @@ Ranked by how commonly the reference adapters ship them and how much UX they unl
 6. **MCP passthrough** (`mcpServers` on `session/new` + `mcpCapabilities`).
 7. **Richer prompt content** — image / embedded `resource` blocks (needs a multimodal model path).
 8. **Diff + location tool rendering** — `diff` content and `locations` for edit tools.
-9. **Usage reporting** (`usage_update`) — the harness already has the internal usage events.
+9. **Usage reporting** (`usage_update`) — the harness already records token usage internally (on `assistant/message`).
 10. **Editor filesystem delegation** (`fs/read_text_file` / `fs/write_text_file`) — lets the agent see unsaved buffers; lower priority since the harness has direct disk access.
 
 ## Out of scope