loosen commit granularity rule in prompts

Replace the strict "one commit per file" guidance with grouping by
related changes, while keeping the small-and-focused intent. Add
explicit guidance on when to include a commit body and how to format
it (blank line separator, ~72 col wrap).

Applied to both backend and frontend prompt templates.

ai/backend_prompt_template.md

@@ -32,18 +32,24 @@ Code patterns to follow:
 - Variable names: use explicit, descriptive names — never single-letter or abbreviated variables (e.g., use $sponsorship not $s, $event not $e)
 
 Git commit style:
-- Present tense, imperative mood (add, create, test, fix)
+- Subject: present tense, imperative mood (add, create, test, fix)
-- Lowercase
+- Subject: lowercase, short (3-6 words)
-- Short (3-6 words)
+- Match subject patterns found in git history
-- Match patterns found in git history
+- Add a body when the change needs explanation beyond the subject —
+  e.g., why the change was made, non-obvious tradeoffs, or notable
+  implementation details. Skip the body for trivial/self-evident commits.
+- Separate subject and body with a blank line; wrap body at ~72 columns
 
 Git commits:
 - Tests should be committed first, before implementation
-- One commit per file - each new file gets its own commit
+- Group related changes together in a single commit (e.g., a new class
-- Make commits SMALL and FREQUENT - every meaningful change should be a commit
+  plus its registration, or a getter plus the property it exposes).
+  Avoid mixing unrelated concerns in one commit.
+- Keep commits small and focused — prefer many small commits over few
+  large ones, but don't artificially split a single logical change
+  across multiple commits
 - Commits are for reviewing and documenting the development of code
-- A commit can be as simple as adding one import, one getter, one property, etc.
+- Don't wait to commit — commit as you go
-- Don't wait to commit - commit as you go
 - Run `php-cs-fixer fix` on worked on directories before committing
 
 Branch naming:

ai/frontend_prompt_template.md

@@ -22,18 +22,24 @@ Code patterns to follow:
 - Variable names: use explicit, descriptive names — never single-letter or abbreviated variables (e.g., use sponsorship not s, event not e)
 
 Git commit style:
-- Present tense, imperative mood (add, create, test, fix)
+- Subject: present tense, imperative mood (add, create, test, fix)
-- Lowercase
+- Subject: lowercase, short (3-6 words)
-- Short (3-6 words)
+- Match subject patterns found in git history
-- Match patterns found in git history
+- Add a body when the change needs explanation beyond the subject —
+  e.g., why the change was made, non-obvious tradeoffs, or notable
+  implementation details. Skip the body for trivial/self-evident commits.
+- Separate subject and body with a blank line; wrap body at ~72 columns
 
 Git commits:
 - Tests should be committed first, before implementation
-- One commit per file - each new file gets its own commit
+- Group related changes together in a single commit (e.g., a new class
-- Make commits SMALL and FREQUENT - every meaningful change should be a commit
+  plus its registration, or a getter plus the property it exposes).
+  Avoid mixing unrelated concerns in one commit.
+- Keep commits small and focused — prefer many small commits over few
+  large ones, but don't artificially split a single logical change
+  across multiple commits
 - Commits are for reviewing and documenting the development of code
-- A commit can be as simple as adding one import, one getter, one property, etc.
+- Don't wait to commit — commit as you go
-- Don't wait to commit - commit as you go
 
 Branch naming:
 - Use kebab-case (e.g., node-page text-page)