fix(ci): drop job-level hashFiles() guards that fail the run before any job

Quoting the store:: filter was necessary but not sufficient: the run
from that fix still completed with zero jobs and GitHub still displayed
the workflow by path rather than by its name, the tell that it never
became a real workflow run.

The cause is 'if: hashFiles(...)' at job level. hashFiles() resolves
against the runner workspace, which does not exist when a job-level if
is evaluated, so the expression errors while the run graph is being
built — the run ends as failure with no jobs and no usable logs.

Both guards were pointless as well as fatal: Cargo.toml and Cargo.lock
are committed and always present in this repo.

cargo-audit.yml carries the identical pattern and the identical
symptom, so it is fixed here too.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/cargo-audit.yml

@@ -19,7 +19,6 @@ jobs:
     name: Dependency audit
     runs-on: ubuntu-latest
     timeout-minutes: 15
-    if: hashFiles('Cargo.lock') != ''
     steps:
       - name: Checkout repository
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4

.github/workflows/db-checks.yml

@@ -33,7 +33,6 @@ jobs:
     name: Migrations + schema drift
     runs-on: ubuntu-latest
     timeout-minutes: 15
-    if: hashFiles('Cargo.toml') != ''
 
     steps:
       - name: Checkout