feat(games): add Rapport model as typed atomic entry for Report

[RebelliousSmile]

Summary

• Introduces Rapport — the atomic narrative element composing a Report, with four fixed types: description, action, discussion, narration
• discussion type requires an existing Character as actor; all other types forbid actor — validated in Rapport.clean() bidirectionally
• HTMX-first UI: inline form on the report detail page, conditional actor field via Alpine.js, delete without page reload

Changes

• Model: Rapport(BaseModel) with RapportKind choices, clean() validation, migration 0010
• Admin: RapportInline on ReportAdmin
• Form: RapportForm with actor queryset scoped to the report's game
• Views: rapport_create (GET+POST), rapport_edit, rapport_delete — all guarded by report.author == request.user
• Templates: rapport_form.html (Alpine.js conditional actor + help link when no characters), partials/rapport_item.html (HTMX swap delete), report_detail.html updated
• Tests: 13 tests — model validation (5) and view access control (8)
• i18n: .po/.mo updated for fr/en

Test plan

• Open a Report as author → "Ajouter un Rapport" button visible
• Add a Description rapport → appears in list without reload
• Add a Discussion rapport → actor dropdown filters to game characters only
• Submit Discussion without actor → inline error, no insert
• Game with no characters → help link to game detail page
• Edit a Rapport → content updates correctly
• Delete a Rapport → removed from DOM via HTMX
• Non-author → 403 on create/edit/delete
• make check → 271 passed, mypy clean, ruff clean

Closes #64

🤖 Generated with Claude Code