Fix dart→flutter in CI; add pre-commit hook and install-hooks task

- ci.yml: dart run/dart test → flutter pub run/flutter test (all 3 jobs)
- hooks/pre-commit: runs flutter analyze + flutter test before every commit
- Taskfile: add install-hooks task (copies hooks/pre-commit → .git/hooks/)
- LATER.md: remove resolved items (enough_mail fork, pre-commit, GH CI)

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

Taskfile.yml

@@ -12,6 +12,13 @@ tasks:
       - sh: test "${DIRENV_DIR#-}" = "{{.TASKFILE_DIR}}"
         msg: "Not in nix dev shell. Run: nix develop"
 
+  install-hooks:
+    desc: Install git hooks from hooks/ into .git/hooks/
+    cmds:
+      - cp hooks/pre-commit .git/hooks/pre-commit
+      - chmod +x .git/hooks/pre-commit
+      - echo "Installed hooks/pre-commit → .git/hooks/pre-commit"
+
   codegen:
     desc: Generate Drift DB code (run after any schema change)
     deps: [_nix-check]