Read feature, release workflow (v0.3.0)

- Read button (desktop and web): reads the tag now, bypassing the status
  cache, and puts its first link or text record into the input field so it
  can be copied to another tag. POST /api/read in the web version.
- Raw memory: every 4-byte page from page 0 (UID, lock bytes, CC, data) in
  hex and ASCII, collapsed by default.
- Content now shows the records and the note together (a locked tag showed
  only "read-only" before); read failures are flagged with read_failed
  instead of matching message text.
- .gitea/workflows/release.yml: on a v* tag, tests and clippy, then Linux
  (ubuntu-22.04, glibc 2.35) and Windows (MinGW cross-build) packages
  attached to the tag's release with its CHANGELOG.md section.
- README: reading, why the reader program runs on the reader's machine,
  releases.

CHANGELOG.md

@@ -0,0 +1,13 @@
+# Changelog
+
+## v0.3.0
+
+First release.
+
+- Desktop app `nfc-writer`: type a link or some text, put a tag on the reader, press **Program**. No browser or network needed.
+- Web version `nfc-writer-web`: the same on a local page at http://127.0.0.1:7252.
+- **Read** reads the tag now and puts its link or text into the field, so it can be copied to another tag. "Raw memory" shows every page of the tag in hex.
+- Writes NDEF links and text to NTAG213/215/216 and MIFARE Ultralight tags, then reads them back to check.
+- Finds the reader by itself: the contactless slot of the ACS ACR1252U, or any other PC/SC contactless reader. `NFC_READER` picks one by name.
+
+Downloads below: Windows and Linux (x86_64). On Linux, install `pcscd` and `libccid` first. For macOS, build from source (see README).