feat: add commit-helper tool to optimize AI commit context

Replaces verbose git command invocations in commit commands with a smart
TypeScript helper that:
- Filters out lockfiles, binary files, and generated content from diffs
- Truncates large diffs intelligently by preserving complete file changes
- Provides structured summaries with file type distribution and change stats
- Shows previews of new files being added

Also adds Fish shell VSCode extension and enables Claude Code panel preference.

home/dot_claude/commands/amend-commit.md

@@ -1,18 +1,11 @@
 ---
-allowed-tools: Bash(git status:*), Bash(git diff:*), Bash(git show:*), Bash(git commit:*)
+allowed-tools: Bash(git commit:*)
 description: Amend the most recent commit (with staged changes and/or message reword)
 ---
 
 ## Context
 
-**Current staged changes:**
-!`git diff --cached --stat`
-
-**Files in most recent commit:**
-!`git show --stat --pretty=format: HEAD | grep -v '^$'`
-
-**Recent commit history (for style reference):**
-!`git log --oneline -5`
+!`commit-helper --amend`
 
 ## Your task
 

home/dot_claude/commands/commit-staged.md

@@ -1,17 +1,11 @@
 ---
-allowed-tools: Bash(git status:*), Bash(git diff:*), Bash(git log:*), Bash(git commit:*)
+allowed-tools: Bash(git commit:*)
 description: Commit currently staged changes with an appropriate message
 ---
 
 ## Context
 
-- Current git status:
-!`git status`
-- Current git diff line count: !`git diff --cached | wc -l`
-- Current git diff (staged changes only):
-!`if [ $(git diff --cached | wc -l) -lt 200 ]; then git diff --cached; else git diff --cached --stat; fi`
-- Recent commits:
-!`git log --oneline -10`
+!`commit-helper --staged`
 
 ## Your task