[MetaROR] Ch3 Choosing the Target Study — author revisions

Author revisions for **Chapter 3 (Choosing the Target Study)** from the MetaROR reviews (R1, R2) and internal notes.

- [x] Move the generalizability/boundary-conditions paragraph out of the Uncertainty section — it disrupts the flow. (R1) (in #37)
- [x] Clarify whether "Uncertainty > Theoretical contribution" and "Uncertainty > Availability of reproductions and replications" are intended as enumerated subsections or parts of the Uncertainty discussion. (R2) (in #37)
- [x] Add a brief mention of "replication packages" with a forward reference to Section 5.1. (R2) (in #37)
- [x] Reconsider citing Soto as evidence of a field's high replicability — at most it tests a small subset of the field. (Lukas) (already removed in 60e9e79)

**Handled in other issues:**
- Move Section 4.1 (Post-Publication Conversations) into Chapter 3; reconsider whether Section 3.4 (Researcher Bias) fits Chapter 3 → *Structural reorganisation & scope*

Review Chapter 3 with the MetaROR reviews (R1, R2) and internal notes, then check issue #37 and commit 60e9e79 for the revisions already handled. Done means confirming the remaining structural reorganisation is tracked under the stated scope issue rather than making changes here.

Written by the indexing model from the issue text.