docs: record Symfony tooling conventions in CLAUDE.md (#81)

[martinydeAI]

Links to issues

Fixes #81.

Description

Extends the Coding practices section (introduced by PR #74) with
three subsections that name the Symfony-native tooling the project
expects agents to reach for first. Each entry is short and
prescriptive — name the tool, when to reach for it, what failure
mode it prevents.

Added subsections, inserted between Defer to symfony.com/doc when implementing Symfony features and Controllers stay thin:

1. Use Symfony Flex for new dependencies. Install via
   task composer -- require <package> so the recipe wires
   config/bundles.php, config/packages/, and .env placeholders.
   Hand-editing composer.json or running composer with
   --no-scripts is the failure mode this rule prevents.
2. Twig components: reuse before creating, prefer
   symfony/ux-twig-component. New reusable markup lives at
   templates/components/<Family>/<Name>.html.twig and is invoked via
   <twig:Family:Name … />, not {% include %} or hand-rolled
   partials. Scan the existing families first — extending a component
   with a new prop almost always beats a near-duplicate that drifts in
   styling.
3. Use Maker Bundle when a recipe exists. Scaffolding work
   (entity, controller, command, form, fixture, voter, event
   subscriber, registration form, etc.) goes through
   task console -- make:<thing>. Hand-rolling boilerplate is the
   failure mode this rule prevents.

Verified locally:

• symfony/flex, symfony/ux-twig-component, and symfony/maker-bundle
  are all already in composer.json, so each rule names tooling the
  project actually has.
• task coding-standards-markdown-check — green.

Screenshot of the result

n/a — docs-only.

Checklist

• My code is covered by test cases. (n/a — docs-only.)
• My code passes our test (all our tests). (n/a — docs-only.)
• My code passes our static analysis suite. (markdown lint passes.)
• My code passes our continuous integration process.

Additional comments or questions

do-not-merge rationale: this PR is stacked on top of #74. Base
is chore/test-method-comments (the head of #74) rather than
develop. Merge order is #74 first, then this PR, after a
quick rebase onto develop. Remove the do-not-merge label once #74
has landed.

---

Details - AI specificities

• Section ordering matters: the three new subsections sit between
  Defer to symfony.com/doc and Controllers stay thin so the
  "where to find guidance → what tooling to reach for → how to shape
  the code" flow reads top-to-bottom.
• The Maker Bundle subsection deliberately references the
  symfony.com/doc rule above ("matches what symfony.com/doc rule
  above points at"), so the two stay aligned conceptually.
• Each rule names a package that's already installed
  (symfony/flex, symfony/ux-twig-component, symfony/maker-bundle)
  — none of them imply a new dependency.