First slice of T-99 (the D-56-path-a IPC server). What this lands:
* lib/src/ipc/paths.dart rewritten — `workspaceSocketPath(root)`
returns the per-workspace path per D-70 (FNV-1a 64-bit hash, hex,
no crypto dep — D-70 amended in this commit to record the hash
choice). Old `defaultSocketPath()` removed; the lone fallback in
facade.dart kept with a clear placeholder pending T-127.
* lib/src/ipc/server.dart — IpcServer class. ServerSocket.listen
accept loop (D-72), 0600 socket + 0700 parent (D-71), stale-node
probe + unlink on start, refuses to clobber a live listener.
* lib/main.dart — IpcServer started after the first dispatcher is
built and swapped on project open (workspace path changes).
Failure logged but non-fatal so the UI still works without IPC.
* 11 server tests + 5 path tests cover socket modes, multi-conn,
stale unlink, live-conflict, idempotent start/stop.
T-99 children downstream of T-124 (T-125 / T-126 / T-127 / T-130)
are now unblocked.
Co-Authored-By: Claude <noreply@anthropic.com>
jpmschweitzerandClaude
c4bccd35a3