[MetaROR] Ch3 Choosing the Target Study — author revisions

[LukasWallrich]

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

• Move the generalizability/boundary-conditions paragraph out of the Uncertainty section — it disrupts the flow. (R1) (in Ch3 editorial fixes: structure, replication packages ref, Soto claim (#16) #37)
• 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 Ch3 editorial fixes: structure, replication packages ref, Soto claim (#16) #37)
• Add a brief mention of "replication packages" with a forward reference to Section 5.1. (R2) (in Ch3 editorial fixes: structure, replication packages ref, Soto claim (#16) #37)
• 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