docs: add release notes for v0.1.0–v0.4.0, v0.6.0 and v0.7.0

Backfill notes for versions that had a tag but no release page, so
every version up to v0.7.1 has a GitHub/Gitea release. Tag v0.7.0 at
45b27d5 (was missing).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/release-notes/v0.1.0.md

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+# v0.1.0 — First release: STEP viewer with measurement & assembly checks
+
+## ✨ New features
+
+**Open your CAD files**
+* Import STEP, STL and DXF — several files at once. STEP assemblies show up as a tree where you can hide/show, recolor or zoom to any part.
+
+**Measure**
+* Point, distance, edge length, face, circle (radius/diameter), angle and face-to-face distance. Values come from the exact CAD geometry wherever it's available.
+
+**Check how parts fit**
+* Two-point align (move), three-point align (rotate + move), rotate 90° about an axis, and an interference check that reports overlaps or the minimum gap between parts.
+
+**More tools**
+* Section view, mm ⇄ inch switch, export measurements to CSV, and save a high-resolution screenshot.
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [commit history](https://github.com/ETWen/STPViewer/commits/v0.1.0)

docs/release-notes/v0.2.0.md

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+# v0.2.0 — Drag parts into place
+
+## ✨ New features
+
+**Drag mode**
+* Press and hold a part with the left mouse button and drag it where you want; release to drop it. Smooth even on very large assemblies, and measurement accuracy is unaffected.
+* Right-drag rotate, wheel zoom and Shift+drag pan still work as before.
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [v0.1.0...v0.2.0](https://github.com/ETWen/STPViewer/compare/v0.1.0...v0.2.0)

docs/release-notes/v0.2.1.md

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+# v0.2.1 — Fix crash after dragging a part
+
+## 🐛 Bug fixes
+
+**No more crash after using drag mode**
+* Clicking anywhere in the view after dragging a part could crash the app. Fixed — you can drag, then measure or select as usual.
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [v0.2.0...v0.2.1](https://github.com/ETWen/STPViewer/compare/v0.2.0...v0.2.1)

docs/release-notes/v0.3.0.md

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+# v0.3.0 — 3-axis gizmo for precise move & rotate
+
+## ✨ New features
+
+**Gizmo manipulator**
+* Select a file in the tree and a gizmo appears at its center: drag the X/Y/Z arrows to move exactly along one axis, or the rotation rings to spin it by any angle — from any viewing angle.
+* Selecting another file moves the gizmo to it.
+
+## ⚠️ Known limitation
+
+* The gizmo can be hidden inside solid parts. (Fixed in v0.3.1 — the gizmo now always stays on top.)
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [v0.2.1...v0.3.0](https://github.com/ETWen/STPViewer/compare/v0.2.1...v0.3.0)

docs/release-notes/v0.4.0.md

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+# v0.4.0 — Faster and more stable
+
+## ✨ Improvements
+
+**Section slider stays responsive on big files**
+* Dragging the section slider on large assemblies no longer freezes the screen — the cut is computed in the background and shown as soon as it's ready.
+
+**Faster placement after moving parts**
+* After dragging or using the gizmo, the part settles into its new position much faster. The interference check's gap calculation is faster too.
+
+## 🐛 Bug fixes
+
+**Errors no longer close the app**
+* If something goes wrong, you now get a message and the app keeps running instead of shutting down. Details are logged to `%LOCALAPPDATA%\STPViewer\error.log`.
+* Import, rotate and interference buttons are disabled while a long task is running, so they can't be triggered twice by accident.
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [v0.3.2...v0.4.0](https://github.com/ETWen/STPViewer/compare/v0.3.2...v0.4.0)

docs/release-notes/v0.6.0.md

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+# v0.6.0 — Export to STL
+
+## ✨ New features
+
+**STL export with a settings dialog**
+* Save the parts on screen — including any alignment or rotation you applied — as an STL mesh for 3D printing or other software.
+* Before exporting you choose: one merged file or one file per input, Binary or ASCII, mm / inch / custom scale, and mesh quality (current or fine).
+* The dialog shows the triangle count and estimated file size live, so you know what you'll get before you hit export.
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [v0.5.0...v0.6.0](https://github.com/ETWen/STPViewer/compare/v0.5.0...v0.6.0)

docs/release-notes/v0.7.0.md

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+# v0.7.0 — Menu bar & customizable quick toolbar
+
+## ✨ New features
+
+**Menu bar**
+* Every feature is now in a menu, grouped by File / View / Measure / Transform / Tools — no more hunting through one long row of buttons.
+
+**Quick toolbar you can customize**
+* The toolbar now holds only the buttons you use most. Pick which ones under **Quick Bar → Customize**; your choice is remembered next time.
+
+**Tidier section controls**
+* The section axis/position bar only appears while section view is on, so it no longer takes up space.
+
+**About dialog**
+* **Help → About** shows the version and a plain-language history of what each release brought.
+
+## 📦 Downloads
+
+Source only — no prebuilt binaries were published for this version. For a ready-to-run build, grab the [latest release](https://github.com/ETWen/STPViewer/releases/latest).
+
+## 🔗 Links
+
+* [Architecture](https://github.com/ETWen/STPViewer/blob/main/ARCHITECTURE.md)
+* [README](https://github.com/ETWen/STPViewer/blob/main/README.md)
+
+**Full changelog:** [v0.6.0...v0.7.0](https://github.com/ETWen/STPViewer/compare/v0.6.0...v0.7.0)