fix: correctness + reliability follow-ups across the intent generation stack

[delchev]

A review of the recent intent-DSL generation work surfaced several defects. Each is fixed at the outermost layer and covered by a test.

Fixes

• checks → HTTP 400 (was 500). Document-level checks (itemsMin/itemsSumEqual) and the roll-up capacity guard threw a raw IllegalStateException, reaching REST as a 500. New SDK type org.eclipse.dirigible.sdk.db.ValidationException, mapped to 400 once in ControllerInvoker (framework-wide; the repository layer stays web-free). The emission IT now asserts an exact 400 so a 500 regression can't hide behind >=400.
• generates sourceStatus: no stale-snapshot clobber. The source status was flipped with a full-row updateWithoutEvent() merge of a snapshot loaded before the target + items were created, silently reverting concurrent writes. Now flips only the status column via the targeted updateProperty primitive and reloads for the -transitioned payload.
• postings: idempotent + resumable. The handler wrote target+items non-atomically and skipped on any existing target → a mid-loop failure left a permanent half-post, and concurrent redelivery could double-post. Cloud-native fix (no cross-step transaction): a complete post is a no-op, a half-post rebuilds its items; concurrent de-dup is best-effort until a UNIQUE back-reference key lands with schema constraint emission, and a genuinely failed post is unwound by a compensation action.
• Classloader leak. staleGenerationViews was a WeakHashMap whose value strongly references its key (the caller class), so entries were never collected and every republish pinned a retired ClientClassLoader. Now invalidated explicitly on each SessionFactory rebuild.
• Harmonia where label resolution. Header/manage dropdowns loaded only the filtered /search set into the option list used for label resolution, so an existing value outside the filter rendered blank on edit; now that one value is fetched by id (preserves the /search perf). Also coerces a boolean /search filter value server-side.
• immutable: true 404-vs-409. A PUT to a non-existent append-only record returned 409 instead of 404 (delete and the status-gated variant were already correct).
• Report filter == normalization no longer corrupts a value literal containing == (normalized only outside single-quoted strings).
• My-shell config.js identity corrected (was a verbatim copy of the application shell's).
• Docs: finish the immutableIn→immutableWhen / documentStatus→function: EntityStatus renames left half-done (README broken TOC anchor, assistant guide, module CLAUDE.md); fix the coverage overstatement.

Tests / verification

• New IntentEngineIT render checks: the resumable posting handler and the targeted generates status flip.
• Tightened IntentEmissionCoverageIT check assertions to exact 400.
• New ControllerInvoker mapping unit test (ValidationException → 400).
• Verified: IntentEmissionCoverageIT, engine-intent unit tests, formatter:validate, and release-profile javadoc all pass.

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