docs: release hygiene — roll 0.3.1, open 0.3.2, refresh stale docs

[jinyeow]

Docs + release-metadata cleanup after the Track 2 foundations landed (#57, #58, #59, #60). No code change; the only functional line is the version prefix.

Two real defects, not just staleness

• v0.3.1 shipped without a CHANGELOG section. The tag sits on the Track 1 commit (refactor(tui): Track 1 — IUiPost seam, VmGuard dedup, DiffPaneComposer extraction (#39, #40, #41) #54), and the [Unreleased] block is that release's content — verified: git show v0.3.1:CHANGELOG.md still reads ## [Unreleased], and nothing has touched the file since. Rolled into a dated ## 0.3.1 — 2026-07-23.
• VersionPrefix was left at 0.3.0 through the 0.3.1 release, so every local and branch build reported 0.3.0-alpha — below the released 0.3.1, inverting the guarantee its own comment makes ("a dev build can't be mistaken for, or installed over, a released one"). Bumped to 0.3.2, with the comment now saying to keep it in step with the newest CHANGELOG section. Verified empirically: dotnet run -c Release -- --version → 0.3.2-alpha+c902111.

New: 0.3.2 section

Honest about what it is — no user-facing change. It carries the dependency bumps (#37, #38) and the four internal foundations for the list + preview workspace (ADR 0024): the pure detail formatters, WorkspaceLayout, the typed ADR 0008 invariants (SingleFlightCache<K,V> / Published<T>), and WorkspaceViewModel. The workspace itself is not enabled — Tab still falls back to today's behaviour until #48 makes the preview visible.

Stale docs refreshed against the code

• README status line — said v0.1.0, three releases behind — and the test count (808 → 1,208, measured on merged main: 375 Core + 833 Tui).
• README dev-install examples that pinned the old 0.3.0 prefix (0.3.0-alpha, 0.3.0-local1, 0.3.0+<sha>).
• CLAUDE.md suite size (~750 → ~1,200).
• The UAT checklist's --version expectation, which contradicted shipped behaviour on both counts: it expected 0.1.0 and "no git-hash suffix", but Program.InformationalVersion() has deliberately kept the 7-char +<sha> since 0.3.0. Rewritten to describe both the release and dev-build shapes.

Deliberately not touched

• HANDOFF.md — its staleness is structural, not a version string: it references a long-dead branch (claude/azure-devops-tui-97d16e) and carries real org names that are pending your scrubbing decision. Fixing only the version would leave the misleading parts in place; its fate is a separate call.
• Historical CHANGELOG sections and docs/PLAN.md milestone checkboxes — those are records, correctly frozen.
• docs/testing/manual-verification.md's run-record table still shows 0.1.0 / 0e103df in an otherwise blank form. Left as-is; it's a record of a past run, not an instruction.

Clean CI-style Release build (--no-incremental, ContinuousIntegrationBuild=true): 0 warnings, 0 errors. Suite 1,208 green.

Follow-up: tag v0.3.2 once this merges, so the tagged commit carries the matching CHANGELOG and prefix.