refactor(cli)!: one shared base config with per-surface overlays

`dsh` shipped two config trees that were 43 rows the same: apps/cli/cordis.yml
composed web as 74 flat rows, while the TUI booted examples/tui-agent/cordis.yml
whose single `@deepseek-ai/dsh-tui-demo` row mounted twelve plugins behind a
twenty-key pass-through Config. Neither file was what its location claimed —
apps/cli hardcoded the "example" as the product default and the "demo" bundle
was the application — and every capability change had to be made twice.

- apps/cli/base.cordis.yml holds the 43 shared rows; tui.cordis.yml and
  web.cordis.yml are patch lists stating only what differs per surface
- overlays apply as SIBLING patch lists at one include level, because include
  patches never cross an include boundary. Precedence: base < surface <
  (--config | personal ~/.dsh/config.yaml) < launcher flag/profile patches
- `--config` now applies an overlay INSTEAD OF the personal one, so a demo or
  test tree never inherits the user's route; new `--config-replace` boots a file
  as the entire tree (the old `--config` behaviour). Both survive /resume
- vendor/include: index each `insert`ed row as it is added so a later patch can
  configure or disable it. Upstream built the id index once before the patch
  loop, leaving every surface-only row — the whole TUI front door — silently
  unpatchable from user config. Logged as local modification 8
- session identity moves to dsh-agent-loop's CONFIGURED_AGENT_IDENTITIES_KEY;
  dsh-tui's MAIN_SESSION_ID_KEY is deleted (only the bundle read it)
- delete examples/tui-agent, examples/cordis-agent, packages/examples/tui-demo;
  TUI tests → apps/cli/tests, cordis e2e → packages/cordis/tool-cordis/tests,
  examples/code-mode survives as an overlay leaf
- `dsh web` gains --config, threaded into AppCLIEntry as an extra overlay

Three latent defects surfaced and are fixed here: the TUI captured the optional
sessionQuery service once at construction and could permanently disable /resume
when it won the mount race; the session-store root silently reverted to a
project-local ./.sessions; --config-replace was dropped by the resume handoff.

Verified by booting each tree through the real Loader (TUI 55 entries, web 75,
zero unsettled) rather than reading YAML. All eight terminal snapshots replay
byte-identically; 14/14 PTY smoke, 112/112 snapshots, 25/25 doc-sync, hygiene
and lint clean.

packages/ui/app-boot/src/index.ts

@@ -94,20 +94,56 @@ export function loadPersonalPatches(
     if ((error as NodeJS.ErrnoException | null)?.code === 'ENOENT') return undefined
     throw new Error(`${binName}: failed to read personal patches ${file}: ${String(error)}`)
   }
+  return parsePatchList(binName, file, content, 'personal patches')
+}
+
+/**
+ * Load a required overlay patch list: a surface overlay (`tui.cordis.yml`) or a
+ * `--config <path>` overlay applied over the shared base. Same file format as
+ * {@link loadPersonalPatches}, but a missing file throws, because the caller
+ * named this file — its absence is a misconfiguration, not "no overlay".
+ * @param binName - the diagnostic prefix on the thrown error.
+ * @param file - absolute path of the overlay file.
+ * @returns the parsed patch list.
+ */
+export function loadOverlayPatches(binName: string, file: string): PatchOptions[] {
+  let content: string
+  try {
+    content = readFileSync(file, 'utf8')
+  } catch (error) {
+    throw new Error(`${binName}: failed to read overlay ${file}: ${String(error)}`)
+  }
+  return parsePatchList(binName, file, content, 'overlay')
+}
+
+/**
+ * Parse one loader patch list: a top-level YAML array of
+ * `@cordisjs/plugin-include` `PatchOptions` (id-targeted config overrides and
+ * `insert` lists, `!!js` expressions allowed). Every shape failure throws,
+ * because a patch file that cannot be applied at all is a misconfiguration; a
+ * single patch whose target row is absent stays a per-entry Loader warning, so
+ * one overlay shared across surfaces does not have to match every tree.
+ * @param binName - the diagnostic prefix on the thrown error.
+ * @param file - the source path, quoted in errors.
+ * @param content - the file's text.
+ * @param label - what to call this list in errors (`personal patches`, `overlay`).
+ * @returns the parsed patch list.
+ */
+function parsePatchList(
+  binName: string, file: string, content: string, label: string,
+): PatchOptions[] {
   let parsed: unknown
   try {
     parsed = yaml.load(content, { schema: personalPatchesSchema })
   } catch (error) {
-    throw new Error(`${binName}: failed to parse personal patches ${file}: ${String(error)}`)
+    throw new Error(`${binName}: failed to parse ${label} ${file}: ${String(error)}`)
   }
   if (!Array.isArray(parsed)) {
-    throw new Error(`${binName}: personal patches ${file} must be a top-level YAML array of loader patch entries`)
+    throw new Error(`${binName}: ${label} ${file} must be a top-level YAML array of loader patch entries`)
   }
-  // A present personal config that cannot apply is a misconfiguration and must
-  // fail loud here — the include only warns per entry at mount.
   parsed.forEach((entry, index) => {
     if (typeof entry !== 'object' || entry === null || Array.isArray(entry)) {
-      throw new Error(`${binName}: personal patches entry ${index + 1} in ${file} must be a mapping (a loader patch entry)`)
+      throw new Error(`${binName}: ${label} entry ${index + 1} in ${file} must be a mapping (a loader patch entry)`)
     }
   })
   return parsed as PatchOptions[]