fix: complete the host redaction, ship missing v2.3/v2.4 changelog, fix README typo, CI the A2A mirror

[NovaLux12]

What this PR does

Four small fixes that close the gaps from the v2.4 audit:

1. Complete the host redaction in archive/v0-schema-notes.md. Commit 8bb9f29 replaced "lee-lab" with "home server" but left "Hetzner VPS in Falkenstein" and "Lambda Cloud" on the same line — the same operator-fingerprint detail the commit message claimed to have scrubbed. Reworded the example to drop provider+datacenter specificity; added an explicit "don't include provider-specific fingerprints" note for future readers of the archived notes.

2. Add missing v2.3 and v2.4 entries to CHANGELOG.md. x_novalux12_card_version was bumped to 2.4 in agent.json but the changelog stopped at v2.2, breaking the README + agent.json cross-reference to CHANGELOG as the source of truth. Entries match the v2.0/v2.1/v2.2 format and describe what the actual diffs did (verified against git show b6c262c and git show f359f27, not inferred). The v2.3 entry also fixes a claim I almost wrote: there was no index.html change in that commit — only the card-version bump + repo addition + .well-known/ drift-sync.

3. Fix the README "supported_interfaces" → "supportedInterfaces" camelCase typo. A2A mirror uses camelCase; the README was a holdover from when the field was in flight.

4. Add agent-card.json (the A2A mirror) to the CI paths: block and smoke-test it on Pages. README markets it as a shipped first-class file, but CI didn't fire on changes to it and didn't verify the served URL worked. Smoke test is shape-level only (the reflectt validator is shape-specific and would reject the A2A card); checks for required top-level fields, that supportedInterfaces is a non-empty list, that Pages serves it as application/json, and that the served bytes match the repo file.

Verification

• python3 scripts/agent-validate.py --schema <schema> ./agent.json — OK (1 non-blocking warning, expected for extensions in non-strict mode)
• python3 scripts/agent-validate.py --schema <schema> ./.well-known/agent.json — OK
• diff <(jq -S . agent.json) <(jq -S . .well-known/agent.json) — byte-identical
• python3 scripts/agent-validate.py --strict --schema <schema> ./examples/agent-kestrel.json — OK

Risk

None. Doc-only, doc-completeness, and CI-gate additions. No spec, schema, validator, or card-content changes. The Pages smoke test for agent-card.json runs even when the file is unchanged (no if: guard) so a transient Pages 502 would fail CI — same as the existing .well-known/agent.json Pages checks.