ci: add pr bot for auto-labeling + rewrite release workflow for semver tags

pr-bot labels PRs by area (scan, nuclei, modules, ci, deps, etc) and size
(xs/s/m/l/xl), posts a summary comment with file stats breakdown.

release workflow now triggers on v* tags instead of every push to main -
extracts version from tag, injects via ldflags, auto-generates changelog
from commits since last release, includes install instructions in the
release body. prerelease detection for rc/beta tags.

Signed-off-by: vmfunc <celeste@linux.com>

.github/labeler.yml

@@ -0,0 +1,44 @@
+ci:
+  - changed-files:
+      - any-glob-to-any-file: ".github/**"
+
+deps:
+  - changed-files:
+      - any-glob-to-any-file:
+          - "go.mod"
+          - "go.sum"
+          - "flake.nix"
+          - "flake.lock"
+
+scan:
+  - changed-files:
+      - any-glob-to-any-file: "internal/scan/**"
+
+nuclei:
+  - changed-files:
+      - any-glob-to-any-file: "internal/nuclei/**"
+
+modules:
+  - changed-files:
+      - any-glob-to-any-file:
+          - "internal/modules/**"
+          - "internal/scan/builtin/**"
+          - "internal/scan/js/**"
+          - "modules/**"
+
+docs:
+  - changed-files:
+      - any-glob-to-any-file:
+          - "**/*.md"
+          - "docs/**"
+
+tests:
+  - changed-files:
+      - any-glob-to-any-file: "**/*_test.go"
+
+config:
+  - changed-files:
+      - any-glob-to-any-file:
+          - "internal/config/**"
+          - ".golangci.yml"
+          - ".editorconfig"