fix: v0.27.18 QA regressions (PR drafts, discovered model catalogs) (#1595)

* fix: v0.27.18 QA regressions in PR drafts and discovered model catalogs

- review: a comment on a PR whose snapshot the page has not seen (after a
  reload) posts inline again; only anchor-checked comments get the Outdated
  label (#1592)
- review: restoring a draft after a push no longer re-marks changed files
  Viewed; the platform-path status post carries draftGeneration
- catalog: always offer opus/sonnet/haiku, reading the default row's family
  and version, so Claude Code 2.1.141 no longer drops Opus (#1593)
- settings: Codex Fast/reasoning re-key to the shown model when the saved one
  was replaced
- codex: read fast mode from serviceTiers (priority/fast)
- ai: Claude sessions no longer wait on model discovery (Bun + Pi share
  createDeferredModelDiscovery); capabilities mark modelsSource so the client
  retries a fallback answer

* fix(ai): wait for discovery when the fallback lacks the requested Claude model

A first Claude session resolved opus[1m] / claude-fable-5-1[1m] onto the
fallback's opus / fable (another context window and billing than later
sessions). In session mode the session now waits for discovery when the list
is still the fallback and does not offer the pick; picks the fallback offers
stay instant. Also stop reading a context size ("Opus 1M context") as the
default row's version.