refactor: standardize config file naming to use .toml extension

Unifies all configuration file naming to consistently use the .toml
extension for better clarity and discoverability.

Changes:
- Rename .ccsync -> .ccsync.toml (project config)
- Rename .ccsync.local -> .ccsync.local.toml (local overrides)
- Update config discovery logic to search for new filenames
- Update all documentation comments and README
- Update .gitignore to reflect new naming convention

This change makes it immediately clear that config files use TOML
format and aligns with common conventions for configuration files.

Author: onsails

.gitignore

@@ -49,7 +49,7 @@ target/
 # tasks/
 
 # Local config overrides (user-specific, not committed)
-.ccsync.local 
+.ccsync.local.toml 
 
 # Devenv
 .devenv*

README.md

@@ -104,7 +104,7 @@ Press **q** or **Ctrl+C** to cancel anytime.
 
 ## ⚙️ Configuration Files
 
-Create a `.ccsync` file in your project to customize sync behavior:
+Create a `.ccsync.toml` file in your project to customize sync behavior:
 
 ```toml
 # Ignore certain files (gitignore-style patterns)
@@ -119,8 +119,8 @@ conflict_strategy = "newer"
 
 **Config file locations** (in order of precedence):
 1. `--config <path>` - Custom config file via flag
-2. `.ccsync.local` - Project-local (gitignored, for personal settings)
-3. `.ccsync` - Project config (committed to repo)
+2. `.ccsync.local.toml` - Project-local (gitignored, for personal settings)
+3. `.ccsync.toml` - Project config (committed to repo)
 4. `~/.config/ccsync/config.toml` - Global config
 
 **CLI flags always override config files.**

crates/ccsync-core/src/config/discovery.rs

@@ -9,9 +9,9 @@ use crate::error::Result;
 pub struct ConfigFiles {
     /// Config from CLI flag (highest precedence)
     pub cli: Option<PathBuf>,
-    /// Project-local config (.ccsync.local)
+    /// Project-local config (.ccsync.local.toml)
     pub local: Option<PathBuf>,
-    /// Project config (.ccsync)
+    /// Project config (.ccsync.toml)
     pub project: Option<PathBuf>,
     /// Global XDG config
     pub global: Option<PathBuf>,
@@ -53,8 +53,8 @@ impl ConfigDiscovery {
             None
         };
 
-        let local = Self::find_file(".ccsync.local");
-        let project = Self::find_file(".ccsync");
+        let local = Self::find_file(".ccsync.local.toml");
+        let project = Self::find_file(".ccsync.toml");
         let global = Self::find_global_config();
 
         Ok(ConfigFiles {

crates/ccsync-core/src/config/merge.rs

@@ -9,8 +9,8 @@
 //!
 //! Configs are loaded from lowest to highest precedence:
 //! 1. Global config (~/.config/ccsync/config.toml)
-//! 2. Project config (.ccsync)
-//! 3. Local config (.ccsync.local)
+//! 2. Project config (.ccsync.toml)
+//! 3. Local config (.ccsync.local.toml)
 //! 4. CLI config (--config flag)
 //!
 //! Higher precedence configs fully override boolean values from lower precedence configs.
@@ -44,8 +44,8 @@ impl ConfigMerger {
     ///
     /// Precedence order (highest to lowest):
     /// 1. CLI config
-    /// 2. .ccsync.local
-    /// 3. .ccsync
+    /// 2. .ccsync.local.toml
+    /// 3. .ccsync.toml
     /// 4. Global config
     ///
     /// # Errors