standardise multi-author support across all forms

- ThesisCreateController: comma-split auteurice, sort alphabetically,
  use setThesisAuthors() instead of hardcoded createThesis() author_id
- Database::createThesis(): removed author_id param and hardcoded insert
- Database::findDuplicateThesis(): accepts array of author names, matches
  any shared author via IN + DISTINCT
- ThesisEditController::save(): sort authors alphabetically on save
- File folder naming: slug from all authors alphabetically sorted
- v_theses_full GROUP_CONCAT: ORDER BY a.name ASC for deterministic display
- Migration 012_author_view_order.sql: rebuilds view with alphabetical order

app/migrations/pending/012_author_view_order.sql

@@ -0,0 +1,59 @@
+-- Rebuild v_theses_full to ORDER BY a.name in the GROUP_CONCAT for authors,
+-- ensuring the view always returns authors alphabetically.
+DROP VIEW IF EXISTS v_theses_full;
+CREATE VIEW IF NOT EXISTS v_theses_full AS
+SELECT
+    t.id,
+    t.identifier,
+    t.title,
+    t.subtitle,
+    t.year,
+    t.is_doctoral,
+    t.objet,
+    o.name as orientation,
+    ap.name as ap_program,
+    ft.name as finality_type,
+    t.synopsis,
+    t.context_note,
+    t.duration_minutes,
+    t.duration_pages,
+    t.file_size_info,
+    at.name as access_type,
+    lt.name as license_type,
+    t.license_id,
+    t.access_type_id,
+    t.jury_points,
+    t.submitted_at,
+    t.defense_date,
+    t.published_at,
+    t.is_published,
+    t.baiu_link,
+    t.banner_path,
+    GROUP_CONCAT(DISTINCT a.name ORDER BY a.name ASC) as authors,
+    GROUP_CONCAT(DISTINCT s.name) as supervisors,
+    GROUP_CONCAT(DISTINCT CASE WHEN ts.role = 'president' THEN s.name END) as jury_president,
+    GROUP_CONCAT(DISTINCT CASE WHEN ts.role = 'promoteur' THEN s.name END) as jury_promoteurs,
+    GROUP_CONCAT(DISTINCT CASE WHEN ts.role = 'lecteur'   THEN s.name END) as jury_lecteurs,
+    GROUP_CONCAT(DISTINCT l.name) as languages,
+    GROUP_CONCAT(DISTINCT fmt.name) as formats,
+    GROUP_CONCAT(DISTINCT tg.name) as keywords,
+    -- First author's email and contact-visibility flag
+    (SELECT a2.email        FROM authors a2 JOIN thesis_authors ta2 ON a2.id = ta2.author_id WHERE ta2.thesis_id = t.id ORDER BY ta2.author_order LIMIT 1) as author_email,
+    (SELECT a2.show_contact FROM authors a2 JOIN thesis_authors ta2 ON a2.id = ta2.author_id WHERE ta2.thesis_id = t.id ORDER BY ta2.author_order LIMIT 1) as author_show_contact
+FROM theses t
+LEFT JOIN orientations o ON t.orientation_id = o.id
+LEFT JOIN ap_programs ap ON t.ap_program_id = ap.id
+LEFT JOIN finality_types ft ON t.finality_id = ft.id
+LEFT JOIN access_types at ON t.access_type_id = at.id
+LEFT JOIN license_types lt ON t.license_id = lt.id
+LEFT JOIN thesis_authors ta ON t.id = ta.thesis_id
+LEFT JOIN authors a ON ta.author_id = a.id
+LEFT JOIN thesis_supervisors ts ON t.id = ts.thesis_id
+LEFT JOIN supervisors s ON ts.supervisor_id = s.id
+LEFT JOIN thesis_languages tl ON t.id = tl.thesis_id
+LEFT JOIN languages l ON tl.language_id = l.id
+LEFT JOIN thesis_formats tf ON t.id = tf.thesis_id
+LEFT JOIN format_types fmt ON tf.format_id = fmt.id
+LEFT JOIN thesis_tags tt ON t.id = tt.thesis_id
+LEFT JOIN tags tg ON tt.tag_id = tg.id
+GROUP BY t.id;