fix: 15 code quality issues — generics, types, locale, dead code, naming (#118)

## Summary

Resolves 15 code-quality issues across 10 files (24 original commits) + 5 follow-up fixes for CI/CI-blocking issues identified by review tools (CodeRabbit, cubic) and CI logs.

### Original PR (commits 1-24)
- 8 atomic type-safety fixes: ActionResult discriminated union, generic dummyDb methods, type-narrow Genkit output via safeParse, i18n locale mapping, generic handleActionError
- 2 utility additions: `getErrorMessage` (safe error extraction), `getZodError` (Zod detection)
- 3 magic-number extractions: `STREAK_MULTIPLIER`, `BONUS_THRESHOLD`, `BASE_XP_PER_WORKOUT`, `XP_PER_COMPLETED_SERIE`, `MS_PER_DAY`, `DAYS_PER_MONTH`
- 4 cleanup commits: `as` cast removal in alunoService, logger.toRecord safe helper, dead placeholder-images files, misleading constant renames
- tsconfig: `noUnusedLocals` + `noUnusedParameters` enabled

### Follow-up fixes (this squash)

| Commit | Issue | Root cause |
|---|---|---|
| fix(actions): add ActionResult<T> | 8 TS2339 (3 client + 5 test) | async-inferred return widened `success: true` literal to `boolean`, broke `if (result.success)` narrowing |
| fix(deps): remove typosquatted 'supabase' | CI Security audit critical | GHSA-x96m-c5fj-q75c flagged unscoped `supabase@^2.92.1` as malware; unused, all Supabase usage is scoped `@supabase/supabase-js` |
| fix(actions): drop broken HistoricoTreinoSchema.parse() | cubic P1 bug I introduced | Zod schema required `exercicios[]` field not present on Prisma model — parse threw on every successful treino finalization |
| fix(actions): dummyDb `as T` cleanup | CodeRabbit MINOR | Redundant `T | null` in `findById<T>` return cast |
| fix(e2e): wrap seed-e2e top-level await in main() | E2E Tests fail | PR commit 9edd2f9 (SonarQube fixes) refactored seed from `.catch().finally()` to `try { await seed() }` — top-level await incompatible with tsx CJS output |

### Verification

- typecheck: 0 errors
- lint: 0 errors, 9 pre-existing warnings (setState-in-effect, unrelated)
- test: 86/86 (13 suites)
- format: clean
- npm audit --audit-level=high: exit 0
- CI: 13/13 checks pass (Quality Gates, Tests & Coverage, SonarCloud, Vercel, E2E, CodeQL, Semgrep ×2, GitGuardian, CodeRabbit, cubic, Analyze JS-TS, Vercel Preview)

Author: EmiyaKiritsugu3

.sisyphus/boulder.json

@@ -0,0 +1,22 @@
+{
+  "active_plan": "/home/emiyakiritsugu/Projetos_Antigravity/PWeb_Project/.sisyphus/plans/pr118-correction-optimization.md",
+  "started_at": "2026-06-04T01:25:46.597Z",
+  "session_ids": [
+    "ses_1776758b8ffe0IKUMawLYpvPQw",
+    "ses_16fc27358ffeNfun8Qdh7fDluf",
+    "ses_16fc259c1ffeUtNcUJmLcWbkvA",
+    "ses_16fc23e3dffeJ6WOz1M0iDykXL",
+    "ses_16fc225bcffe8abQwLq23BbDq2",
+    "ses_16fa87119ffe70sEei10acP95M",
+    "ses_16fa2e3f1ffe8viXu177SRNzjC",
+    "ses_16fa213a6ffeMyoy60MLCpUBRz",
+    "ses_16fa173bfffeerYy4m153uWUfJ",
+    "ses_16fa10d14ffe4dXS00EPOklz5M",
+    "ses_16fa09c45ffe6T4ncs74X2Hm0y",
+    "ses_16fa008ebffeHZQKKVydt0uUhc",
+    "ses_16f9f8481ffenZzCAX6sheyvdu"
+  ],
+  "plan_name": "pr118-correction-optimization",
+  "agent": "atlas",
+  "task_sessions": {}
+}

.sisyphus/evidence/wave0-baseline.txt

@@ -0,0 +1,8 @@
+> vitest run
+ RUN  v4.1.6 /home/emiyakiritsugu/Projetos_Antigravity/PWeb_Project
+ Test Files  10 passed (10)
+      Tests  71 passed (71)
+   Start at  22:26:33
+   Duration  1.27s (transform 812ms, setup 698ms, import 1.40s, tests 212ms, environment 7.15s)
+(node:165263) [DEP0205] DeprecationWarning: `module.register()` is deprecated. Use `module.registerHooks()` instead.
+(Use `node --trace-deprecation ...` to show where the warning was created)

.sisyphus/evidence/wave0-constants.txt

@@ -0,0 +1,3 @@
+src/lib/data.ts:124:    const STREAK_MULTIPLIER = 0.7;
+src/lib/data.ts:125:    const BONUS_THRESHOLD = 0.05;
+src/lib/data.ts:129:      alunos: Math.floor(totalAlunos * (STREAK_MULTIPLIER + idx * BONUS_THRESHOLD)),