fix: normalize paths before deduping intent plan steps (#41)

[bigknoxy]

Rebuilt replacement for #71, which could not be merged. Closes #41.

The bug

generatePlan deduped reference files by raw string. The same file reached as src/a.ts, ./src/a.ts, and /abs/proj/src/a.ts produced one plan step per spelling. Worse, a reference to the definition file spelled differently from the definition escaped the !== definition.file filter and got renamed a second time.

Adds src/core/path-normalize.ts (normalizePath, pathsEqual) and routes both refFiles computations in generatePlan through it.

Why this replaces #71 rather than updating it

#71 introduced these helpers as src/core/paths.ts. That branch was cut at fb1172e, before paths.ts existed on main; main then added it in #54 and #65 as the write-boundary module — assertWritable, safeWrite, atomicWrite, findProjectRoot, PathDeniedError, and the deny-list that no flag overrides (~/.ssh, ~/.aws, /etc, shell rc files, the telemetry log).

Seven modules import it: router.ts, hash-edit.ts, diff-engine.ts, locking.ts, plan-executor.ts, verify.ts, index.ts. #71 arrived as new file mode 100644 at that path, so landing it as authored would have deleted every write guard in the codebase. That is the source of its CONFLICTING status, and a plausible conflict resolution ("take theirs") silently produces exactly that outcome.

git rebase origin/main on #71 hits an add/add conflict on paths.ts where resolving in commit order renames main's write boundary. Rebuilding on current main was the safer path. The helpers now live in a separate module so the two concerns cannot collide again.

Also dropped from #71

• The remove-parameter dedupe test — main refuses that operation outright (UnsupportedIntentError, fix(intent): report unresolved plan steps instead of injecting placeholder comments #66), so the test could not run.
• An unused relative import, unused beforeEach/afterEach imports, an unused cwd local.
• The undefined-only guard in pathsEqual, which made the relation inconsistent: (null, undefined) compared false while (null, null) and (null, "") compared true. normalizePath already collapses every nullish and blank form to "", so the guard was redundant and wrong.

Added coverage

The two non-trivial branches were untested in #71. Now covered: cwd itself, paths outside cwd staying absolute, a sibling directory sharing a cwd prefix not being mistaken for a child, and the full nullish/blank equality matrix.

Verification

Mutation-tested: reverting either normalization call site fails both new intent tests. The suite is 614 pass / 0 fail; bun run lint:docs is green.

Known constraint (documented, not changed)

normalizePath returns cwd-relative for paths under cwd and absolute otherwise, so its output depends on process.cwd(). That is fine for this use — deduping within a single generatePlan call — but makes it unsafe as a persisted key. locking.ts is deliberately cwd-independent for that reason. Recorded in the CLAUDE.md module map so the distinction survives.

🤖 Generated with Claude Code

[bigknoxy]

🎉 This PR is included in version 4.0.6 🎉

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