fix(git): accept native git flags in add command (including -A)

[FlorianBruniaux]

Problem

• rtk git add -A failed with "unexpected argument '-A' found"
• Git flags like -A, -p, --all were rejected by Clap parser
• Only filenames could be passed to git add

Solution

• Add allow_hyphen_values = true to Add command args (following PR fix: pass git flags transparently to git command #5 pattern)
• Change Add enum variant from Add { files } to Add (unified with other git commands)
• Modify run_add() to accept args slice and pass all arguments to git
• Add exit code propagation for consistency with other git commands

Impact

• ✅ All native git add flags now work: -A, -p, --all, --update, etc.
• ✅ Maintains RTK compact output format ("ok ✓ 2 files changed, ...")
• ✅ Preserves backward compatibility (no args defaults to ".")

Testing

• Manual: rtk git add -A works correctly
• All existing tests pass (154 passed)
• Smoke tests unchanged (git add not included in test-all.sh)

Files Changed

• src/main.rs: Updated Add command to accept hyphen values
• src/git.rs: Simplified Add enum and updated run_add() to handle all args

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Enables rtk git add to pass through native git add flags (e.g., -A, --all) by relaxing Clap parsing and routing all remaining args directly to git add.

Changes:

• Update GitCommands::Add to capture trailing args and accept hyphen-prefixed values.
• Simplify GitCommand::Add to a unit variant and pass args via git::run(...).
• Update run_add() to forward all args to git add and propagate non-zero exit codes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/main.rs	Adjusts Clap parsing for git add to accept hyphenated flags as positional args.
src/git.rs	Refactors Add command plumbing and forwards args directly to git add, with exit code propagation on failure.

Comments suppressed due to low confidence (1)

src/git.rs:480

• git add can be interactive (e.g. -p/--patch, -i/--interactive). Using Command::output() does not attach a TTY and will typically fail or hang for these modes. To actually support those flags, run git add with inherited stdio (e.g. stdin/stdout/stderr inherit + status()/spawn().wait()), then compute the staged stat afterward if desired.

            cmd.arg(arg);
        }
    }

    let output = cmd.output().context("Failed to run git add")?;

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[Copilot]

This help text claims “supports all git add flags like -A, -p, --all…”, but (1) -p/--patch is interactive and currently won’t work with the Command::output() implementation, and (2) some short flags collide with RTK global flags (e.g. -u is taken by ultra_compact, -v by verbosity). Consider rewording to avoid “all flags” (or document the collisions and recommend long forms like --update).