fix(mcp): add titleFixWriter for Windsurf stdio compatibility

[cmdaltctr]

This PR adds a titleFixWriter that wraps stdout in the MCP server to fix three issues with Windsurf (and potentially other IDE) integration:

1. Missing newline after JSON-RPC responses — The default server.ServeStdio writes JSON without a trailing newline. Clients relying on line-delimited JSON-RPC (like Windsurf) hang waiting for the message to complete.
2. Tool title in wrong location — Windsurf expects title at the tool root level, but mcp-go places it inside annotations. The writer moves it to the correct location.
3. Missing $schema in inputSchema — Windsurf requires $schema for tool discovery. The writer injects it if absent.

Changes from previous version

This PR was previously scoped to also include a global-mode fallback for mcp-serve. That has been dropped since the upstream --workspace flag (#100) and resolveMCPTarget provide a better solution. This PR now focuses solely on the titleFixWriter fix in mcp/server.go.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 32.36%. Comparing base (a322537) to head (2073bc7).
⚠️ Report is 64 commits behind head on main.

Files with missing lines	Patch %	Lines
mcp/server.go	0.00%	25 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #104      +/-   ##
==========================================
+ Coverage   27.16%   32.36%   +5.20%     
==========================================
  Files          32       40       +8     
  Lines        3711     6303    +2592     
==========================================
+ Hits         1008     2040    +1032     
- Misses       2620     4094    +1474     
- Partials       83      169      +86     

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[yoanbernabeu]

Hi @cmdaltctr, thanks for this contribution!

The PR currently has merge conflicts with main. Could you rebase your branch on the latest main to resolve them?

Everything else looks good — CI is green (only codecov/patch fails due to coverage on new code, which is not blocking). We'll be happy to merge once the conflicts are resolved!

[cmdaltctr]

Hi @yoanbernabeu, thanks for the review!

I've rebased onto the latest main and scoped down the PR to focus only on the titleFixWriter fix in mcp/server.go.

The global-mode fallback logic I originally included in cli/mcp_serve.go has been dropped — the --workspace flag and resolveMCPTarget from #100 provide a much better solution for that use case.

What remains is a single focused change: replacing server.ServeStdio with a custom writer that fixes three Windsurf compatibility issues (missing newline, title placement, $schema injection).