fix: Prevent bot self-trigger infinite loops in all workflows

CRITICAL FIX: Bot was triggering itself causing 10+ duplicate runs

Problem:
- When bot posts comments containing @codebot (e.g., help responses, PR reviews)
- Workflows trigger on those bot comments
- Bot responds again with @codebot mention
- Infinite loop → 10+ duplicate workflow runs → excessive API costs

Solution:
- Added github.event.comment.user.login != 'Bartender' to all workflow conditions
- Prevents bot from reacting to its own comments
- Bot username 'Bartender' is now hardcoded in workflows

Changes:
- .gitea/workflows/ai-comment-reply.yml: Added bot username check
- .gitea/workflows/ai-chat.yml: Added bot username check
- .gitea/workflows/ai-issue-triage.yml: Added bot username check
- CLAUDE.md: Documented bot self-trigger prevention and username update instructions
- README.md: Added Step 3 to bot customization with critical warning

Impact:
- Eliminates infinite loop scenarios
- Prevents excessive API costs from duplicate runs
- Workflows only trigger on human user comments

Note: If bot username changes from 'Bartender', all three workflow files must be updated.

CLAUDE.md

@@ -190,7 +190,7 @@ Workflows are located in `.gitea/workflows/` and are **mutually exclusive** to p
 
 - **enterprise-ai-review.yml** - Triggered on PR open/sync
 - **ai-issue-triage.yml** - Triggered ONLY on `@codebot triage` in comments
-- **ai-comment-reply.yml** - Triggered on specific commands: `help`, `explain`, `suggest`, `security`, `summarize`, `review-again`, `setup-labels`
+- **ai-comment-reply.yml** - Triggered on specific commands: `help`, `explain`, `suggest`, `security`, `summarize`, `changelog`, `explain-diff`, `review-again`, `setup-labels`
 - **ai-chat.yml** - Triggered on `@codebot` mentions that are NOT specific commands (free-form questions)
 - **ai-codebase-review.yml** - Scheduled weekly analysis
 
@@ -201,6 +201,20 @@ Workflows are located in `.gitea/workflows/` and are **mutually exclusive** to p
 
 This prevents the issue where all three workflows would trigger on every `@codebot` mention, causing massive duplication.
 
+**CRITICAL: Bot Self-Trigger Prevention**
+
+All workflows include `github.event.comment.user.login != 'Bartender'` to prevent infinite loops. Without this check:
+- Bot posts comment mentioning `@codebot`
+- Workflow triggers, bot posts another comment with `@codebot`
+- Triggers again infinitely → 10+ duplicate runs
+
+**If you change the bot username**, update all three workflow files:
+- `.gitea/workflows/ai-comment-reply.yml`
+- `.gitea/workflows/ai-chat.yml`
+- `.gitea/workflows/ai-issue-triage.yml`
+
+Look for: `github.event.comment.user.login != 'Bartender'` and replace `'Bartender'` with your bot's username.
+
 **Note**: Issue triage is now **opt-in** via `@codebot triage` command, not automatic on issue creation.
 
 Key workflow pattern: