docs/ als ausgelieferter Hintergrund-Ort; Decision-Seiten bleiben in kb/, Decay-Skip fuer concept_type: decision (4.3.0, #38)

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- instructions/kb-profiles.md
- kb/CONVENTIONS.md
- kb/concepts/COLLECTION.md
- tools/CONTRACT.md
- tools/chemenu/commands/confidence_decay.py
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/tests/test_confidence_decay.py
- tools/chemenu/tests/test_dist_cmd.py

kb/CONVENTIONS.md

@@ -62,7 +62,8 @@ There is no `## Siehe auch` region any more. It was the reciprocal half of a bid
 - Human-readable titles with spaces: `Hybrid Search.md`, `Gitea Actions.md` - not kebab-case.
 - Singular for entities: `ha-core.md`, not `ha-cores.md`.
 - Comparison pages read as a comparison: `Go vs Rust.md`.
-- ADRs are prefixed: `adr-001-use-go-modules.md`.
+- A decision (`concept_type: decision`) is named like any other concept - no `adr-NNN-` prefix.
+  See [kb/concepts/COLLECTION.md § Decisions](concepts/COLLECTION.md#decisions).
 - Prefer readability over convention when the two conflict.
 
 What to name a thing: projects use their repository or common name; systems a descriptive