feat: major overhaul of agent architecture and CLI experience (v3.0.0)

- Refactor agent to use LangChain middleware and streaming outputs
- Implement interactive Rich UI with file staging wizard
- Add TODO scanning feature for staged diffs
- Replace custom tools with standard filesystem and shell middlewares
- Update project version to 3.0.0 and refresh assets

BREAKING CHANGE: The agent architecture and CLI interaction flow have been completely redesigned.

Author: lguibr

ascii-art.txt

@@ -0,0 +1,16 @@
+ ....                        ++*++                       :::::
+..............              ++++++              -:::::::-:- :::
+.............:..              +**              ==--::-  :::::::
+  ...       :...           =++++++=            ---
+            ....      ***+++++++++++++++       ::-
+             ...     ***+++****++++++++++*     ::-
+             ...     ***+++****+++++++++++     :::       -----
+             ...::::-+**++   **+++  ++++++=---=:----------- ---
+               ...-:-+**+++++**++++++++++++-::==---------------
+              ...    ***++++++*+++++++*++* :::- -------  -----
+             ::::     ####***********###*  ----  ------
+  .....      ...        ###**####****##   -----:  ---    -----
+.........   ...               +++        :::::::: ---- ---------
+...   .....:..       ++++++++**+        :::-   ::-  ------   ---
+..........            +**+++            -:::::::::     ---------
+ .......                                  -:::::         ------

assets/commitaai.gif

@@ -3,7 +3,7 @@
 
 # This __version__ string is read by hatchling during the build process
 # Make sure to update it for new releases.
-__version__ = "2.2.2"
+__version__ = "3.0.0"
 
 # The importlib.metadata approach is generally for reading the version
 # of an *already installed* package at runtime. We don't need it here