Fill coverage gaps in chapters 1-11

Audited each chapter file against actual LLPSI Familia Romana content
using parallel reviewers (Claude general-purpose subagents, codex, gemini).
Each chapter gained missing vocabulary, grammar points, common-error
patterns, and exercise types. ~190 lines added across 11 files.

Highlights per chapter:
- c1: geography proper nouns, -us fem. exceptions, num-question answer pattern
- c2: -er paradigm contrast (puer/vir/liber), -que rewrite drill
- c3: interrog. vs. relative quem, neque rewrite
- c4: nullus/UNUS NAUTA, -ius vocative, eius/suus contrast
- c5: relative pron. (nom.), suus agreement, -ae ambiguity
- c6: passus 4th-decl preview, mille/milia, autem postpositive
- c7: cui drill, plenus + gen., quod (because/relative/interrog.) trap
- c8: hic/ille discourse force, UNUS NAUTA class, quantus/quot trap
- c9: stem recovery from gen., ipse emphasis target, sub + abl. for location
- c10: fera vs. ferus, abesse/adesse/ire infinitives, quia/quod synonymy
- c11: full posse paradigm, dat. of reference (mihi dolet), gaudere syntax

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

llpsi-c2.md

@@ -9,6 +9,7 @@ If invoked with a topic (e.g. `/llpsi-c2 genitive`), focus there. Otherwise mix.
 **Nouns** (with gen. + gender):
 - *vir, virī* m. (man); *puer, puerī* m. (boy); *fīlius -ī* m.; *dominus -ī* m. (master); *servus -ī* m. (slave); *liber, librī* m. (book); *titulus -ī* m.
 - *fēmina -ae* f.; *puella -ae* f.; *familia -ae* f.; *fīlia -ae* f.; *domina -ae* f. (mistress); *ancilla -ae* f. (slave-girl); *pāgina -ae* f.
+- *Cornēlius -ī* m. (neighbor character).
 - (Already from cap. I, kept for context.)
 
 **Family words**: *pater, māter, fīlius, fīlia, līberī* (children, pl. only).
@@ -46,6 +47,13 @@ If invoked with a topic (e.g. `/llpsi-c2 genitive`), focus there. Otherwise mix.
 
 6. **Numbers with gender**: *duo virī, duae ancillae, duo oppida; trēs virī, trēs ancillae, tria oppida.* (*duo* and *trēs* inflect; ūnus already known to inflect.)
 
+7. **2nd-decl. *-er* nouns — two patterns**:
+   - **Drops -e- in oblique**: *liber, librī, librō* (and *magister, magistrī*).
+   - **Keeps -e-**: *puer, puerī, puerō*; *vir, virī, virō*.
+   - No rule predicts which — must be memorized per word.
+
+8. **Genitive of proper names** (drill explicitly): *Iūlius → Iūliī*; *Aemilia → Aemiliae*; *Mārcus → Mārcī*; *Quīntus → Quīntī*.
+
 ## Common error patterns
 
 - **Genitive vs. nom. pl. confusion**: student parses *fīliī* as gen. sg. when it's nom. pl. (or vice versa). Always disambiguate by what's around it.
@@ -53,6 +61,10 @@ If invoked with a topic (e.g. `/llpsi-c2 genitive`), focus there. Otherwise mix.
 - **Missing -ōrum in gen. pl.**: student says "of the slaves" as *servī* (gen. sg.) — must be *servōrum*.
 - **Gender of *liber***: it's masculine despite ending in -er; gen. is *librī*. Easy trap.
 - **Wrong gender of *duo***: student says *duo ancillae* — should be *duae ancillae*.
+- ***-er* paradigm cross-contamination**: dropping the *e* in *puer* (*\*prī*) by analogy with *liber → librī*, or keeping it in *liber* (*\*liberī*). Memorize per word.
+- **Overusing *et***: *Mārcus et Quīntus et Iūlia* is grammatical but Ørberg prefers *-que* on the last item: *Mārcus, Quīntus Iūliaque*.
+- **Confusing *quī?* (m. pl.) with *quis?* (sg.)**: *quis est?* (one person) vs. *quī sunt?* (multiple men).
+- ***cuius* is invariant**: students invent *\*cuiae* by analogy with adjective endings — wrong; *cuius* covers all genders.
 
 ## Exercise menu
 
@@ -64,6 +76,10 @@ If invoked with a topic (e.g. `/llpsi-c2 genitive`), focus there. Otherwise mix.
 6. **Spot the error**: "Numerus ancillae magnus est." → should be *ancillārum* (gen. pl., to mean "the number of slave-girls").
 7. **Possessive agreement**: "How would Iūlia say 'my mother'?" → *māter mea.*
 8. **Parse**: present a word in context and ask for case + number (+ gender if ambiguous).
+9. **Family-tree Q&A**: "Quis est pater Mārcī?" → *Iūlius.* "Quot līberī sunt in familiā Iūliī?" → *trēs līberī sunt.*
+10. ***-er* paradigm contrast**: produce gen. sg. of *puer, vir, liber* side-by-side → *puerī, virī, librī* (note *liber* drops *e*).
+11. ***-que* rewrite drill**: rewrite "Mārcus et Iūlia et Quīntus" using *-que* → *Mārcus, Iūlia Quīntusque.*
+12. **Number-with-noun agreement**: "two girls, two boys, two towns" → *duae puellae, duo puerī, duo oppida.*
 
 ## Session start