feat(pdf): extract standalone PDF ingest package (ESRC-WP-0001)

Bootstrap evidence-source from the citation-evidence src/source PDF slice.

- Headless core (src/pdf): ingest/extract/fingerprint, importing domain
  contracts from @citation-evidence/engine/shared (no local copies)
- Browser upload helpers isolated under src/browser behind a ./browser
  entry point, with an eslint boundary keeping the core browser-free
- pnpm/TS/vitest/eslint scaffold; 52 tests (contract + determinism)
- Fixtures resolved from the sibling citation-evidence checkout, not
  duplicated (real PII) — see docs/ADR-0002; suites skip when absent
- Boundary + fixture decisions recorded as docs/ADR-0001 / ADR-0002
- README/SCOPE rewritten; capability.infotech.pdf-evidence-ingest
  registered, NO_CAPABILITIES removed
- Follow-on workplans ESRC-WP-0002..0004 queued; ESRC-WP-0001 finished

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,25 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "lib": ["ES2022", "DOM"],
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "strict": true,
+    "noImplicitOverride": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noEmit": true,
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "isolatedModules": true,
+    "skipLibCheck": true,
+    "resolveJsonModule": true,
+    "verbatimModuleSyntax": true,
+    "types": ["node"]
+  },
+  "include": ["src", "tests", "vitest.config.ts", "eslint.config.js"],
+  "exclude": ["node_modules", "dist"]
+}