feat(ultraplan-local): Spor 2 — HANDOVER-CONTRACTS.md + PreCompact-hook (P0 progress.json drift fix)

Reconciles divergence after parallel-session race: includes both Spor 1 wiring (validators inn i 4 commands + 1 agent) og Spor 2 (HANDOVER-CONTRACTS.md + PreCompact-hook).

Spor 1 wiring (re-applied etter rebase):
- /ultrabrief-local Phase 4g — brief-validator post-write
- /ultraplan-local Phase 1 — brief-validator --soft + research-validator --dir + architecture-discovery
- planning-orchestrator Phase 5.5 — plan-validator --strict erstatter 3 grep -cE-kall
- /ultraexecute-local Phase 2.3 (--validate) — plan-validator + progress-validator
- YAML-parser-utvidelse: list-of-dicts (must_contain), støtter v1.7 template-format

Spor 2 NEW:
- docs/HANDOVER-CONTRACTS.md (~310 linjer) — single source of truth for de 5 pipeline-handover-formatene m/ faste sub-headinger (Producer / Consumer / Path / Frontmatter schema / Body invariants / Validation strategy / Versioning / Failure modes)
- hooks/scripts/pre-compact-flush.mjs (NY) — fikser dokumentert P0 i docs/ultraexecute-v2-observations-from-config-audit-v4.md:
  * Fyrer på PreCompact-event (CC v2.1.105+)
  * Lokaliserer progress.json under .claude/projects/*/
  * Sammenligner stored current_step mot git log {session_start_sha}..HEAD
  * Atomisk write (tmp + rename), monoton — current_step kan aldri reduseres
  * Aldri blokkerer compaction (exit 0)
- hooks/hooks.json registrerer PreCompact-hooken

Resultat: /ultraexecute-local --resume virker nå etter context compaction selv ved skill-driven execution.

Docs:
- README.md (plugin): "Quality infrastructure", "Handover contracts", "PreCompact resume integrity"
- CLAUDE.md (plugin): peker til HANDOVER-CONTRACTS.md + dokumenterer pre-compact-flush
- README.md (marketplace root): bullet-liste over Spor 2-deliverables (resolved merge-konflikt fra parallell-sesjon)

Tester: 109 grønn (ingen regresjon).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugins/ultraplan-local/README.md

@@ -498,6 +498,14 @@ A doc-consistency test (`tests/lib/doc-consistency.test.mjs`) pins prose-vs-sour
 
 Borrowed pattern from `llm-security` (commit `97c5c9d`); extending the plugin should preserve the invariants the test pins.
 
+### Handover contracts
+
+`docs/HANDOVER-CONTRACTS.md` is the single source of truth for the file formats that pass between the four pipeline commands (brief → research → plan → execute). When you fork the plugin or extend a stage, that document tells you what every producer must write and what every consumer is allowed to assume. It also documents the *external* contract for `architecture/overview.md` (owned by the separate `ultra-cc-architect` plugin) — discovery only, drift-warn never drift-fail.
+
+### PreCompact resume integrity (CC v2.1.105+)
+
+The `pre-compact-flush.mjs` hook directly fixes the documented P0 in `docs/ultraexecute-v2-observations-from-config-audit-v4.md`: in skill-driven execution, `progress.json` could fall behind git reality before context compaction, breaking `/ultraexecute-local --resume` after long conversations. The hook fires on every PreCompact event, locates any `progress.json` under `.claude/projects/`, compares stored `current_step` against `git log --oneline {session_start_sha}..HEAD`, and atomically writes a fresh checkpoint (`tmp + rename`, monotonic only) when git is ahead. Never blocks compaction.
+
 ## Known limitations
 
 **Infrastructure-as-code (IaC) gets reduced value.** The exploration agents are designed for application code. Terraform, Helm, Pulumi, CDK projects will get a plan, but agents like `architecture-mapper` and `test-strategist` produce less useful output for IaC. Use ultraplan-local for the structural plan, then supplement IaC-specific steps manually.