docs: README zieht die sources-Areas nach (Nachzug zu #66)

Files changed:
- README.md

README.md

@@ -112,8 +112,15 @@ chemenu/
 │   │   ├── workflows/
 │   │   ├── decisions/
 │   │   └── problems/
-│   ├── sources/        # COLLECTION.md - source summaries, no areas by choice
-│   └── comparisons/    # COLLECTION.md - comparison pages
+│   ├── sources/        # COLLECTION.md + INDEX.md + areas below
+│   │   ├── transcripts/
+│   │   ├── analyses/
+│   │   ├── articles/
+│   │   ├── documents/
+│   │   ├── notes/
+│   │   ├── trackers/
+│   │   └── unclassified/
+│   └── comparisons/    # COLLECTION.md - comparison pages, no subtype axis
 ├── work/               # WORKSHOP: one directory per multi-session run, tracked
 │   └── CONTRACT.md     # Run keys, required files, how a run closes
 ├── reports/            # DERIVED: lint reports, traces, eval scores. Gitignored
@@ -144,8 +151,12 @@ names. That is also what makes the catalog's shard threshold do anything - `inde
 splits **per area**, so a collection with no areas keeps one table however large it grows.
 `wikitool lint` reports such a collection once it is past the threshold, as a recommendation
 rather than an error, together with the split its subtype field would produce; it stays quiet
-when the split would not actually help. `kb/sources/` is the worked example of the second case
-and deliberately has no areas. `COLLECTION.md` never
+when the split would not actually help. `kb/comparisons/` is the worked example of a collection
+that stays flat - it has no subtype field for a `layout:` to key on at all. A *lopsided* subtype
+field is a different case and is fixed rather than left flat: `kb/sources/` looked lopsided only
+because `source_type` had a schema `default:` that the compiler applied whenever nobody chose a
+value, and once that was removed and the pages reclassified it split into six real areas
+(Gitea #66). `COLLECTION.md` never
 appears outside `kb/` - the other layers carry a `CONTRACT.md` or a root type-spec instead. A stage may carry
 both a `README.md` and a `CONTRACT.md`: they have different readers. The README is for humans
 working *on* that layer, the contract is what binds an agent working *with* it.