docs(fix): correct nav link case + relative-path level

Gitea (and any case-sensitive filesystem) was rendering the [Top]
nav links in /docs as broken because of two bugs:

1. Case-sensitivity: 22 links used '../README.md' (all-uppercase)
   but the actual file is 'docs/Readme.md' (capital R, lowercase
   rest). 21 guide_*.md nav bars were affected, plus 1 internal
   cross-link in Readme.md itself. Works on Windows (case-
   insensitive) but broken on Linux/Gitea.

   Fix: 22 occurrences across 22 files changed
   '../README.md' -> '../Readme.md'

2. Wrong relative-path level: 16 links used '../../conductor/...'
   from 'docs/guide_*.md' to reach 'conductor/'. This goes up 2
   levels to 'projects/', which doesn't exist. The correct path
   from 'docs/guide_*.md' to 'conductor/' is 1 level up
   ('../conductor/...'). 12 unique patterns across 10 files
   affected.

   Fix: 16 occurrences across 10 files changed
   '../../conductor/' -> '../conductor/'

3. Bonus: 1 planned-guide link in guide_context_curation.md
   referenced a never-written 'guide_context_presets.md'. The
   ContextPreset schema is now fully covered in the new
   'guide_context_aggregation.md' (per the 2026-06-08 docs
   refresh). Fix: link target updated.

No content was changed, only link paths. 24 files, 37 link
replacements, 37 deletions.

Verification:
- All .md links in docs/ now resolve to existing files
  (validated by path-resolution check from each file's directory)
- The 3 new guides from the previous docs refresh commit
  (guide_discussions.md, guide_state_lifecycle.md,
  guide_context_aggregation.md) had the case bug inherited from
  guide_architecture.md's existing nav pattern; their top-of-file
  nav bars are now correct
- The 21 pre-existing guide nav bars that had the same bug
  (all 21 of them, except the 3 that used the correct case:
  guide_mma.md, guide_simulations.md, guide_tools.md) are now
  also fixed
- Inter-guide links (e.g. [Discussions](guide_discussions.md))
  were not affected; they were always correct because both the
  link text and the actual filename are lowercase

This is a docs-only fix. No code modified.

docs/guide_mma.md

@@ -572,5 +572,5 @@ See [guide_workspace_profiles.md](guide_workspace_profiles.md) (placeholder; wri
 - **[guide_app_controller.md](guide_app_controller.md)** — How the AppController drives MMA via `_cb_start_track`, `_do_generate`, `_process_event_queue`
 - **[guide_context_aggregation.md](guide_context_aggregation.md)** — The `aggregate.py:build_tier3_context` variant used by MMA workers
 - **[guide_discussions.md](guide_discussions.md)** — The Discussion system; MMA worker prompts are built from the active discussion
-- **[conductor/tracks/nagent_review_20260608/report.md §9](../../conductor/tracks/nagent_review_20260608/report.md)** — Deep-dive on the MMA sub-conversation pattern vs nagent's `<nagent-conversation>` tag; **the highest-priority future-track is to extract MMA's `run_worker_lifecycle` into a reusable `SubConversationRunner` for 1:1 discussions** (per user-flagged want)
-- **[conductor/tracks/nagent_review_20260608/nagent_takeaways_20260608.md §3 and §10](../../conductor/tracks/nagent_review_20260608/nagent_takeaways_20260608.md)** — Actionable patterns for the SubConversationRunner; the design constraint that sub-agents return a *concise artifact* (not a full transcript) is baked into the recommendation
+- **[conductor/tracks/nagent_review_20260608/report.md §9](../conductor/tracks/nagent_review_20260608/report.md)** — Deep-dive on the MMA sub-conversation pattern vs nagent's `<nagent-conversation>` tag; **the highest-priority future-track is to extract MMA's `run_worker_lifecycle` into a reusable `SubConversationRunner` for 1:1 discussions** (per user-flagged want)
+- **[conductor/tracks/nagent_review_20260608/nagent_takeaways_20260608.md §3 and §10](../conductor/tracks/nagent_review_20260608/nagent_takeaways_20260608.md)** — Actionable patterns for the SubConversationRunner; the design constraint that sub-agents return a *concise artifact* (not a full transcript) is baked into the recommendation