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/test-e2e.yml

@@ -0,0 +1,30 @@
+name: Integration / E2E Tests
+
+on:
+    push:
+        branches: [main]
+    workflow_dispatch:
+
+concurrency:
+    group: e2e-${{ github.event.pull_request.number || github.sha }}
+    cancel-in-progress: true
+
+permissions:
+    contents: read
+
+env:
+    CARGO_TERM_COLOR: always
+
+jobs:
+    integration-tests:
+        name: Integration / E2E Tests
+        runs-on: blacksmith-2vcpu-ubuntu-2404
+        timeout-minutes: 30
+        steps:
+            - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+            - uses: dtolnay/rust-toolchain@631a55b12751854ce901bb631d5902ceb48146f7 # stable
+              with:
+                  toolchain: 1.92.0
+            - uses: useblacksmith/rust-cache@f53e7f127245d2a269b3d90879ccf259876842d5 # v3
+            - name: Run integration / E2E tests
+              run: cargo test --test agent_e2e --locked --verbose