Fix Full Table eligibility — accept ordinary verbs, reject orto

The eligibility filter required every form's regularity tag to equal
"regular", but the data uses four labels:
  - regular   (179 forms — curated paradigm verbs)
  - ordinary  (50,992 forms — pattern-following verbs like hablar, comer)
  - irregular (8,653)
  - orto      (176 — orthographic spelling changes like busqué)

Result was a 27-combo eligible pool, ~26 of which were -ir verbs in
present tense — every Full Table prompt landed on the same handful of
verbs.

Pulled the rule into a SharedModels function (FullTableEligibility) so
it's testable in isolation. Accepts "regular" + "ordinary" (both mean
"follows the pattern"); rejects "irregular" and "orto". 9 unit tests
cover the matrix including edge cases (incomplete forms, mixed labels,
unknown values).

PracticeSessionService.makePromptIfFullyRegular now delegates to
FullTableEligibility, sorting forms by personIndex so the regularity
array lines up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Conjuga/SharedModels/Sources/SharedModels/FullTableEligibility.swift

@@ -0,0 +1,31 @@
+import Foundation
+
+/// Decides whether a (verb, tense) combo is eligible for the Full Table
+/// practice mode. Pulled out of `PracticeSessionService` so the rule can be
+/// unit tested in isolation.
+public enum FullTableEligibility {
+
+    /// `VerbForm.regularity` values understood by the data set.
+    public enum Regularity: String, Sendable {
+        case regular   // paradigm-teaching verbs (small curated set)
+        case ordinary  // pattern-following verbs (the bulk of the dataset)
+        case irregular
+        case orto      // orthographic spelling change (e.g. busqué)
+    }
+
+    /// Returns true when the given (verb, tense) combo is a candidate for
+    /// Full Table — i.e. it follows the regular pattern with no irregularity
+    /// and no orthographic spelling change.
+    ///
+    /// The conjugation must be present in all 6 person slots; missing forms
+    /// disqualify the combo.
+    ///
+    /// Accepted: `regular` (paradigm-teaching verbs) and `ordinary`
+    /// (pattern-following verbs — `hablar`, `comer`, `vivir`, etc.).
+    /// Rejected: `irregular` and `orto` (orthographic spelling changes).
+    public static func isFullyRegular(regularities: [String]) -> Bool {
+        guard regularities.count == 6 else { return false }
+        let acceptable: Set<String> = ["regular", "ordinary"]
+        return regularities.allSatisfy { acceptable.contains($0) }
+    }
+}

Conjuga/SharedModels/Tests/SharedModelsTests/FullTableEligibilityTests.swift

@@ -0,0 +1,74 @@
+import Testing
+@testable import SharedModels
+
+@Suite("FullTableEligibility")
+struct FullTableEligibilityTests {
+
+    // MARK: - Should be eligible
+
+    @Test("all-ordinary verb (e.g. hablar present) is eligible")
+    func allOrdinary() {
+        // hablar present: hablo / hablas / habla / hablamos / habláis / hablan
+        let r = Array(repeating: "ordinary", count: 6)
+        #expect(FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    @Test("all-regular paradigm verb (e.g. vivir present) is eligible")
+    func allRegular() {
+        // vivir present is tagged "regular" in the curated subset
+        let r = Array(repeating: "regular", count: 6)
+        #expect(FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    @Test("mixed regular + ordinary across persons is eligible")
+    func mixedRegularOrdinary() {
+        // The data never actually mixes these, but it shouldn't matter if it
+        // did — both labels mean "follows the regular pattern".
+        let r = ["regular", "ordinary", "regular", "ordinary", "regular", "ordinary"]
+        #expect(FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    // MARK: - Should NOT be eligible
+
+    @Test("any irregular form rejects the combo")
+    func anyIrregular() {
+        var r = Array(repeating: "ordinary", count: 6)
+        r[3] = "irregular"
+        #expect(!FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    @Test("orthographic spelling change rejects the combo (excluded by design)")
+    func anyOrto() {
+        // buscar preterite: yo "busqué" carries an orto tag for the c→qu shift.
+        // Per design choice, orto verbs are NOT eligible for Full Table.
+        var r = Array(repeating: "ordinary", count: 6)
+        r[0] = "orto"
+        #expect(!FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    @Test("all-irregular rejects")
+    func allIrregular() {
+        let r = Array(repeating: "irregular", count: 6)
+        #expect(!FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    // MARK: - Edge cases
+
+    @Test("incomplete forms (fewer than 6 persons) are rejected")
+    func incompleteForms() {
+        let r = Array(repeating: "ordinary", count: 5)
+        #expect(!FullTableEligibility.isFullyRegular(regularities: r))
+    }
+
+    @Test("empty input is rejected")
+    func empty() {
+        #expect(!FullTableEligibility.isFullyRegular(regularities: []))
+    }
+
+    @Test("unknown regularity value is rejected (defensive default)")
+    func unknownValue() {
+        var r = Array(repeating: "ordinary", count: 6)
+        r[2] = "garbage_value"
+        #expect(!FullTableEligibility.isFullyRegular(regularities: r))
+    }
+}