feat(ci): Add Fedora RPM package build workflow

Build and publish RPM packages for Fedora using rpkg and official
rust-packaging macros. GPG sign packages with Ed25519 repository key
and deploy to Forgejo package registry.

Publishes packages to organised groups:
- continuwuity (binary): base group (stable/dev/branch-name)
- continuwuity-debuginfo: GROUP-debug
- continuwuity (source RPM): GROUP-src

Workflow triggers on pushes to relevant paths and version tags (v*).
Tagged releases use clean version numbers (v1.2.3 becomes 1.2.3-1)
while branch builds use git SHA versioning.

Include GPG public key for package verification and documentation
for RPM repository configuration and installation methods.

docs/deploying/fedora.md

@@ -0,0 +1,201 @@
+# RPM Installation Guide
+
+Continuwuity is available as RPM packages for Fedora, RHEL, and compatible distributions.
+
+The RPM packaging files are maintained in the `fedora/` directory:
+- `continuwuity.spec.rpkg` - RPM spec file using rpkg macros for building from git
+- `continuwuity.service` - Systemd service file for the server
+- `RPM-GPG-KEY-continuwuity.asc` - GPG public key for verifying signed packages
+
+RPM packages built by CI are signed with our GPG key (Ed25519, ID: `5E0FF73F411AAFCA`).
+
+```bash
+# Import the signing key
+sudo rpm --import https://forgejo.ellis.link/continuwuation/continuwuity/raw/branch/main/fedora/RPM-GPG-KEY-continuwuity.asc
+
+# Verify a downloaded package
+rpm --checksig continuwuity-*.rpm
+```
+
+## Installation methods
+
+**Stable releases** (recommended)
+
+```bash
+# Add the repository and install
+sudo dnf config-manager addrepo --from-repofile=https://forgejo.ellis.link/api/packages/continuwuation/rpm/stable/continuwuation.repo
+sudo dnf install continuwuity
+```
+
+**Development builds** from main branch
+
+```bash
+# Add the dev repository and install
+sudo dnf config-manager addrepo --from-repofile=https://forgejo.ellis.link/api/packages/continuwuation/rpm/dev/continuwuation.repo
+sudo dnf install continuwuity
+```
+
+**Feature branch builds** (example: `tom/new-feature`)
+
+```bash
+# Branch names are sanitized (slashes become hyphens, lowercase only)
+sudo dnf config-manager addrepo --from-repofile=https://forgejo.ellis.link/api/packages/continuwuation/rpm/tom-new-feature/continuwuation.repo
+sudo dnf install continuwuity
+```
+
+**Direct installation** without adding repository
+
+```bash
+# Latest stable release
+sudo dnf install https://forgejo.ellis.link/api/packages/continuwuation/rpm/stable/continuwuity
+
+# Latest development build
+sudo dnf install https://forgejo.ellis.link/api/packages/continuwuation/rpm/dev/continuwuity
+
+# Specific feature branch
+sudo dnf install https://forgejo.ellis.link/api/packages/continuwuation/rpm/branch-name/continuwuity
+```
+
+**Manual repository configuration** (alternative method)
+
+```bash
+cat << 'EOF' | sudo tee /etc/yum.repos.d/continuwuity.repo
+[continuwuity]
+name=Continuwuity - Matrix homeserver
+baseurl=https://forgejo.ellis.link/api/packages/continuwuation/rpm/stable
+enabled=1
+gpgcheck=1
+gpgkey=https://forgejo.ellis.link/continuwuation/continuwuity/raw/branch/main/fedora/RPM-GPG-KEY-continuwuity.asc
+EOF
+
+sudo dnf install continuwuity
+```
+
+## Package management
+
+**Automatic updates** with DNF Automatic
+
+```bash
+# Install and configure
+sudo dnf install dnf-automatic
+sudo nano /etc/dnf/automatic.conf  # Set: apply_updates = yes
+sudo systemctl enable --now dnf-automatic.timer
+```
+
+**Manual updates**
+
+```bash
+# Check for updates
+sudo dnf check-update continuwuity
+
+# Update to latest version
+sudo dnf update continuwuity
+```
+
+**Switching channels** (stable/dev/feature branches)
+
+```bash
+# List enabled repositories
+dnf repolist | grep continuwuation
+
+# Disable current repository
+sudo dnf config-manager --set-disabled continuwuation-stable  # or -dev, or branch name
+
+# Enable desired repository
+sudo dnf config-manager --set-enabled continuwuation-dev  # or -stable, or branch name
+
+# Update to the new channel's version
+sudo dnf update continuwuity
+```
+
+**Verifying installation**
+
+```bash
+# Check installed version
+rpm -q continuwuity
+
+# View package information
+rpm -qi continuwuity
+
+# List installed files
+rpm -ql continuwuity
+
+# Verify package integrity
+rpm -V continuwuity
+```
+
+## Service management and removal
+
+**Systemd service commands**
+
+```bash
+# Start the service
+sudo systemctl start conduwuit
+
+# Enable on boot
+sudo systemctl enable conduwuit
+
+# Check status
+sudo systemctl status conduwuit
+
+# View logs
+sudo journalctl -u conduwuit -f
+```
+
+**Uninstallation**
+
+```bash
+# Stop and disable the service
+sudo systemctl stop conduwuit
+sudo systemctl disable conduwuit
+
+# Remove the package
+sudo dnf remove continuwuity
+
+# Remove the repository (optional)
+sudo rm /etc/yum.repos.d/continuwuation-*.repo
+```
+
+## Troubleshooting
+
+**GPG key errors**: Temporarily disable GPG checking
+
+```bash
+sudo dnf --nogpgcheck install continuwuity
+```
+
+**Repository metadata issues**: Clear and rebuild cache
+
+```bash
+sudo dnf clean all
+sudo dnf makecache
+```
+
+**Finding specific versions**
+
+```bash
+# List all available versions
+dnf --showduplicates list continuwuity
+
+# Install a specific version
+sudo dnf install continuwuity-<version>
+```
+
+## Building locally
+
+Build the RPM locally using rpkg:
+
+```bash
+# Install dependencies
+sudo dnf install rpkg rpm-build cargo-rpm-macros systemd-rpm-macros
+
+# Clone the repository
+git clone https://forgejo.ellis.link/continuwuation/continuwuity.git
+cd continuwuity
+
+# Build SRPM
+rpkg srpm
+
+# Build RPM
+rpmbuild --rebuild *.src.rpm
+```