treewide: replace nix with mise for tooling

- Add .mise.toml with Rust 1.85
- Update CI/release workflows to use jdx/mise-action
- Remove all nix/devenv files (flake.nix, devenv.nix, etc.)
- Remove .envrc (mise handles activation natively)
- Update README installation section

Author: aster-void

.envrc

@@ -14,19 +14,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: jdx/mise-action@v2
       - run: cargo build
 
   test:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: jdx/mise-action@v2
       - run: cargo test
-
-  nix:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: DeterminateSystems/nix-installer-action@main
-      - run: nix run . -- --help

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: jdx/mise-action@v2
       - run: cargo build --release
 
       - name: Upload artifact

.github/workflows/release.yml

@@ -1,19 +1,5 @@
-# Devenv
-.devenv*
-devenv.local.nix
-devenv.local.yaml
-
-# direnv
-.direnv
-
 # pre-commit
 .pre-commit-config.yaml
 
-
 # Added by cargo
-
 /target
-
-# nix
-result
-result-*

.gitignore

@@ -0,0 +1,2 @@
+[tools]
+rust = "1.85"

.mise.toml

@@ -10,21 +10,15 @@ Self-updating cron scheduler that pulls job definitions from git.
 cargo install --path .
 ```
 
-### Nix
+### mise
 
-```bash
-# Run directly
-nix run github:ut-code/rollcron -- /path/to/repo
-
-# Install
-nix profile install github:ut-code/rollcron
+This project uses [mise](https://mise.jdx.dev/) for tool version management. After installing mise:
 
-# Open a shell
-nix shell github:ut-code/rollcron
+```bash
+mise install
+cargo install --path .
 ```
 
-I recommend installing this via https://github.com/aster-void/nix-repository for build cache.
-
 ## Quick Start
 
 1. Create `rollcron.yaml` in your repository: