feat(cli): emit self-contained before/after sequence comparison bundles

[tryingET]

Fork CI tracking PR for upstream getappmap#2388.

This branch adds appmap sequence-diagram-compare, which emits a portable before/after/merged sequence comparison bundle with stable change IDs and mapped base/head/diff event IDs.

Independent dogfood

tryingET/appmap-node run 32134789649 is fully green and exercised this command end to end:

• built the CLI branch;
• built exact base/head appmap-node revisions;
• recorded and sanitized deterministic AppMaps;
• verified a clean control comparison;
• verified exactly one added authorize call;
• uploaded the portable artifact;
• downloaded the real generated bundle into the companion VS Code test;
• opened it in the Electron extension host;
• packaged the dogfood VSIX;
• passed the review-action publisher/skill harness.

Artifacts:

• appmap-pr-comparison — ID 9323691826, SHA-256 0cd6a4fc0a11f38713e6739fbab585e2f553dd6cece002d33c4d53a66651e0e9
• appmap-comparison-vsix — ID 9323896071, SHA-256 7855a61259d588b0ee12807143f6dd63c15a33708f67722a474db07207b531f0

Upstream review: getappmap#2388

This fork PR exists only to provide an additional CI target while the upstream first-time-contributor workflows await approval.

[tryingET]

Final comparison contract freeze

The branch now defines and publishes appmap.comparison schema version 1, a view-neutral foundation for all four AppMap comparison views.

Contract guarantees

• reserved views: dependency, sequence, trace, and flame
• independent per-view schema versions
• one shared canonical BehavioralChange[]
• deterministic chg_<20-hex> IDs, with _2, _3, … only for indistinguishable repeats
• event references plus elementIds for structural changes without events
• producer, scenario, revision, recording, capability, and navigation metadata
• runtime validation before serialization
• published JSON Schema and TypeScript declarations
• compatibility README and schema changelog
• conformance fixtures for clean, added, removed, changed, and reordered behavior

Final dogfood

tryingET/appmap-node run 32226024667 is fully green and pinned to this exact commit:

aab690a5c4c01802551993718b508718c1139c11

Results:

• @appland/models comparison contract: 12 tests passed
• CLI sequence comparison producer: 2 tests passed
• clean control: 0 changes
• visual fixture: exactly 1 added authorize call
• generated artifact opened in VS Code Electron
• viewer VSIX and publisher/skill harness passed

Artifacts:

• schema/data bundle 9355642181 — SHA-256 9e7e2d34d75dcae27a6a60f7b9d22d90daa04233af4a2358ddda2ae38b6ffac0
• viewer VSIX 9355691022 — SHA-256 c845728666068d97d58864bb091e14bf0cc33ed314097a2d776cc00745429379

The artifact embeds the exact dependency lock and the complete frozen contract, making this state reproducible for the monorepo migration.