fix(memory): parse Windows backslash paths in memory/cc path locators

[YOMXXX]

Summary

Fixes #2012 (Issues 1 & 2). The memory system is non-functional on Windows: parsePath() in packages/opencode/src/memory/paths.ts matches /memory/... with a forward-slash-only regex, but Windows returns backslash paths (\memory\...). Every file fails to parse → reconcileMemory() skips all → memory_fts stays empty → the memory tool always returns "No matches".

Fix: normalize \ → / before the forward-slash regex match in both parsePath() and parseCcPath() (which has the same Windows failure). No-op for POSIX paths.

const normalized = absPath.replace(/\\/g, "/")
const m = normalized.match(/\/memory\/(global|projects|sessions).../)

Test Plan

• New Windows (backslash) tests: parsePath global/project-MEMORY/session-checkpoint; parseCcPath CC notes.
• bun test test/memory/paths.test.ts test/memory/cc-paths.test.ts — 38 pass (existing forward-slash tests green).
• bun typecheck — clean.

Notes

• Issue Bug: Memory system broken on Windows — empty FTS + no project isolation #2012's Issue 3 (all sessions share project_id = "global", no project isolation) is a separate architectural concern (记忆功能没有区分不同项目 #902) — out of scope here.