chore(ci): externalize workflow scripts and relocate main flow doc (#722)

* feat: Add GitHub Actions workflows for security audits, CodeQL analysis, contributor updates, performance benchmarks, integration tests, fuzz testing, and reusable Rust build jobs

- Implemented `sec-audit.yml` for Rust package security audits using `rustsec/audit-check` and `cargo-deny-action`.
- Created `sec-codeql.yml` for CodeQL analysis scheduled twice daily.
- Added `sync-contributors.yml` to update the NOTICE file with new contributors automatically.
- Introduced `test-benchmarks.yml` for performance benchmarks using Criterion.
- Established `test-e2e.yml` for running integration and end-to-end tests.
- Developed `test-fuzz.yml` for fuzz testing with configurable runtime.
- Created `test-rust-build.yml` as a reusable job for executing Rust commands with customizable parameters.
- Documented main branch delivery flows in `main-branch-flow.md` for clarity on CI/CD processes.

* ci(workflows): update workflow scripts and rename for clarity; remove obsolete lint feedback script

* chore(ci): externalize workflow scripts and relocate main flow doc

.github/workflows/pr-intake-checks.yml

@@ -0,0 +1,30 @@
+name: PR Intake Checks
+
+on:
+    pull_request_target:
+        types: [opened, reopened, synchronize, edited, ready_for_review]
+
+concurrency:
+    group: pr-intake-checks-${{ github.event.pull_request.number || github.run_id }}
+    cancel-in-progress: true
+
+permissions:
+    contents: read
+    pull-requests: write
+    issues: write
+
+jobs:
+    intake:
+        name: Intake Checks
+        runs-on: blacksmith-2vcpu-ubuntu-2404
+        timeout-minutes: 10
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+
+            - name: Run safe PR intake checks
+              uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+              with:
+                  script: |
+                      const script = require('./.github/workflows/scripts/pr_intake_checks.js');
+                      await script({ github, context, core });