Align nested modules with the shared v0.20.1 release

[jilio]

Align the SQLite, Durable Streams and OpenTelemetry modules with the already published root v0.20.1, using verified checksums. Finalize the 0.20.1 changelog date and comparison link following PR #59.

Examples stay on v0.20.0 until the nested v0.20.1 tags are published and verified, so standalone CI does not request versions that do not exist yet. Their final alignment follows separately before the common release announcement.

Validation:

• Each affected nested module passed standalone formatting, build, vet, normal tests and race tests on its minimum Go version: SQLite 1.24.2, Durable Streams 1.25.1, OpenTelemetry 1.25.12. Each selected the published root v0.20.1 through normal module/checksum verification.
• All six workspace modules passed formatting, build, vet, normal tests and race tests with Go 1.25.12.
• Core/state coverage remains 100.0%; SQLite coverage is 97.6%.

[claude]

Review

This is a clean, mechanical release-alignment PR — no Go source logic is touched, only dependency version pins and changelog metadata. I verified the changes by inspecting the diff and cross-checking module files directly (I wasn't able to execute go fmt/go test/coverage in this sandboxed review session, so those CLAUDE.md-mandated checks should still be confirmed by CI before merge).

What the diff does:

• otel/go.mod, stores/durablestream/go.mod, stores/sqlite/go.mod: bump github.com/jilio/ebu from v0.20.0 → v0.20.1, with matching go.sum hash updates.
• CHANGELOG.md: finalizes the [0.20.1] entry date (Unreleased → 2026-09-12) and fixes the compare link (v0.20.0...HEAD → v0.20.0...v0.20.1), consistent with the format used by every prior release entry.

Things I checked that look correct:

• The three nested modules that were bumped (otel, stores/sqlite, stores/durablestream) are exactly the ones that import the root module and were affected by the v0.20.1 release in Align SQLite read settings and literal filename handling #59.
• The examples modules (examples/observability, examples/observability/generator) intentionally remain on v0.20.0, matching the PR description's stated rationale (nested example tags for v0.20.1 aren't published yet). This is consistent — good to confirm that's still true at merge time.
• go.mod/go.sum changes are paired correctly in each module (no orphaned go.sum entries or mismatched go.mod requires).
• The changelog date/link edits match the established formatting pattern for prior releases.

Minor notes (non-blocking):

• Since this PR's only risk surface is the go.sum hashes, it'd be worth a sanity check that go build ./.../go test ./... were run fresh on this exact diff in CI (the PR description says validation was done, just flagging it as the one thing worth double-checking given checksums can't be eyeballed for correctness).
• No test coverage impact since no behavioral code changed — coverage numbers cited in the description (100% core, 97.6% SQLite) are unaffected by this PR.

Overall: looks safe to merge pending green CI.