chore: remove outdated documentation and prep notes

- Deleted several draft and prep documents related to benchmarks, authority DPoP & mTLS implementation, Java analyzer observation, link-not-merge determinism tests, replay operations, and crypto provider registry.
- Updated the merge semver playbook to reflect current database schema usage.
- Cleaned up the technical development README to remove references to obsolete documents and streamline guidance for contributors.

docs/modules/mirror/prep-56-001-thin-bundle.md

@@ -1,22 +0,0 @@
-# Mirror Thin Bundle Prep — PREP-MIRROR-CRT-56-001 (Draft)
-
-Status: Draft (2025-11-20)
-Owners: Mirror Guild (Assembler)
-Scope: Capture requirements to start thin bundle v1 when upstream Sprint 110.D artefacts land.
-
-## Dependencies
-- Sprint 110.D assembler foundation (missing in repo).
-- Trust root list and TUF metadata locations from release pipeline.
-
-## Proposed thin bundle v1 shape
-- Container: tar.gz deterministic; root manifest `mirror.thin.manifest.json`.
-- Fields: `bundle_id`, `schema_version`=`mirror.thin.v1`, `created_at`, `source_registry`, `artifacts[] {digest, media_type, size}`, `trust_roots[]`, optional `attestations[]`.
-- Merkle root over files for audit.
-
-## Open decisions
-- Exact artifact set included in “thin” scope (SBOM only vs SBOM+metadata).
-- Required signatures (DSSE/Sigstore) and signer identities.
-- Retention/GC policy for thin bundles.
-
-## Handoff
-Use this as the PREP artefact for PREP-MIRROR-CRT-56-001; update when assembler foundation drops so schema can be finalized and aligned with `docs/modules/mirror/thin-bundle-assembler.md`.