fix: pin pierre diffs dependency

[benvinegar]

Summary

• Pin @pierre/diffs to 1.2.2 instead of allowing newer 1.x releases.
• Document the npm install fix in the changelog.

Why

Fresh npm i -g hunkdiff resolves the previous semver range to @pierre/diffs@1.2.6, which was published with catalog: dependency specifiers that npm cannot install.

Verification

• bun run typecheck
• bun test scripts/prebuilt-package-helpers.test.ts
• Local npm pack + global install smoke with npm@11.5.1

This PR description was generated by Pi using GPT-5.1

[greptile-apps]

Greptile Summary

Pins @pierre/diffs to exactly 1.2.2 in both package.json and bun.lock, preventing npm from resolving to the broken 1.2.6 release that uses catalog: specifiers incompatible with npm. A matching changelog entry is added under [Unreleased] > Fixed.

• package.json / bun.lock: range ^1.2.2 → exact pin 1.2.2 to block resolution of 1.2.6 which cannot be installed with npm.
• CHANGELOG.md: new ### Fixed bullet in the [Unreleased] section documenting the regression and the fix.

Confidence Score: 5/5

Safe to merge — the change is a minimal, targeted dependency pin with no logic changes.

Only three files are touched: the manifest pins one dependency to its exact tested version, the lock file is updated in lockstep, and the changelog records the fix in the correct unreleased section. The changes are internally consistent and address a concrete install breakage.

No files require special attention.

Important Files Changed

Filename	Overview
package.json	Pins @pierre/diffs from ^1.2.2 to exact 1.2.2; change is consistent with bun.lock.
bun.lock	Lock file updated to reflect exact 1.2.2 pin, consistent with package.json.
CHANGELOG.md	New fix entry correctly placed under [Unreleased] > ### Fixed; format matches the rest of the file.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["npm i -g hunkdiff"] --> B{Resolve @pierre/diffs}
    B -- "Before: ^1.2.2" --> C["Resolves to 1.2.6\n(catalog: specifiers)"]
    C --> D["❌ npm install fails"]
    B -- "After: 1.2.2 (exact)" --> E["Resolves to 1.2.2\n(standard deps)"]
    E --> F["✅ npm install succeeds"]

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