feat: add global Claude Code instructions

Tracks ~/.claude/CLAUDE.md in the repo under claude/CLAUDE.md.
The original is replaced by a symlink back to this file.

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

README.md

@@ -1,25 +1,28 @@
 # dotfiles
 
-Shared shell configuration.
+Shared shell and tool configuration.
 
 ## Scope
 
-This repo currently tracks only shared zsh UI behavior.
+Tracked files:
+- `.zshrc` — shared zsh UI behavior
+- `claude/CLAUDE.md` — global Claude Code instructions
 
-Tracked file:
+This repo is intentionally small. Machine-specific setup stays local unless explicitly promoted into shared config later.
-- `.zshrc`
-
-This repo is intentionally small. Machine-specific shell setup stays in the local `~/.zshrc` unless explicitly promoted into shared config later.
 
 ## Local Setup
 
-Local `~/.zshrc` is expected to source this repo-managed file:
+**zsh**: Local `~/.zshrc` sources this repo:
 
 ```zsh
 source "$HOME/Projekte/dotfiles/.zshrc"
 ```
 
-That keeps the repo as the source of truth for shared prompt and shell UX, while local environment setup can remain machine-specific.
+**Claude Code**: `~/.claude/CLAUDE.md` is a symlink to this repo:
+
+```zsh
+ln -s "$HOME/Projekte/dotfiles/claude/CLAUDE.md" ~/.claude/CLAUDE.md
+```
 
 ## What Lives Here
 

claude/CLAUDE.md

@@ -0,0 +1,29 @@
+# Personal preferences
+
+## Workflow
+
+- **Specs, plans, and design docs go into the repo they describe.** When
+  brainstorming, plan-mode, or any flow produces a persistent document
+  (design spec, implementation plan, ADR, etc.), the final destination is
+  always the working tree of the project it belongs to — typically
+  under `docs/` (or wherever the project conventionally keeps them).
+  Scratch locations like `~/.claude/plans/<slug>.md` are fine *during*
+  plan mode, but the moment plan mode exits with an approved artifact,
+  copy it into the repo and `git commit` it. Don't ship a feature
+  while its spec or plan still lives only in a scratch file. If a
+  project's `AGENTS.md` / `CLAUDE.md` specifies a different directory,
+  that wins.
+
+## Tooling
+
+- **`ccc` for semantic code search.** Repos containing a
+  `.cocoindex_code/` directory are indexed by
+  [`ccc`](https://github.com/cocoindex-io/cocoindex-code). Reach for
+  it on conceptual questions ("where is X used / which files do Y /
+  what handles Z"), where a keyword grep would miss indirect usage:
+  `ccc search '<concept>' --path '**'`. Pass `--path '**'` — without
+  it, results are filtered to the current working directory's
+  subtree. The `ccc` skill has the full reference;
+  `grep`/`rg`/`find` remain fine for exact-string lookups.
+
+@RTK.md