Add Scenario progress foundation

[Roman Lutz (romanlutz)]

Summary

Adds persistent versioned Scenario run plans, stable logical work identities, backend-authoritative sizing, incremental progress cursors, and corrected timing/resume semantics. Planned units deduplicate repeated logical objectives while execution attempts remain observable.

What this layer adds

• Versioned normalized ScenarioRunPlan and progress models persisted in Scenario result metadata.
• Stable atomic-group and seed-unit identities shared across planning and execution.
• Incremental, run-bound opaque progress cursors with bounded delta paging.
• Backend-authoritative sizing, corrected timing, resume validation, and legacy reconstruction.
• Keyword-only multi-parameter APIs and typed completion callbacks.

Visual contract

Stack

This is 1 of 7 in the Scenario GUI stack and targets main. Later layers add the catalog/launch UI, live progress, history, FIFO scheduling, configuration sizing, and result details.

Layer	Scope	Validated snapshot
1	Progress foundation (this PR)	2f6c7155
2	Catalog and launch	6cfc1454
3	Live progress	58c5c569
4	Run history	71726039
5	FIFO scheduling	478db50c
6	Configuration sizing	4b81ccf5
7	Result details	29a0ec02

See the full implementation, screenshots, walkthrough, validation, and operational notes. Actual PR links will replace the snapshot links after all seven drafts exist.

Validation

• Complete backend unit suite: 15,212 passed, 120 skipped.
• Complete frontend suite: 68/68 suites, 1,286/1,286 tests; lint, TypeScript, and production build passed.
• Mock Playwright with retries disabled: 91 passed, 0 failed, 0 skipped.
• Seeded Playwright with retries disabled: 62 passed, 0 failed, 0 skipped.
• All configured pre-commit hooks passed; distinguished-engineer review approved the final stack.

Compatibility note

Prepended-conversation request converters now default to user-role messages, and strict non-chat targets can reject excluded roles. This intentional behavior change is isolated in this foundation layer.

[Roman Lutz (romanlutz)]

Superseded by same-repository draft #2372 so the seven dependent PRs can be registered as a native GitHub stack.